DESC:CROSS REFERENCE TO RELATED APPLICATION
This application is based on and derives the benefit of Indian Provisional Application 202141030569 filed on 07-Jul-2021, the contents of which are incorporated herein by reference.

TECHNICAL FIELD
[001] The embodiments herein relate to systems and methods for pressurized air supply to foil air bearings in one of a power transmission device (gearbox) and a turbo-machinery device, thereby enhancing the performance of the foil air bearings resulting in enhanced performance of the power transmission device or turbo-machinery device.

BACKGROUND
[002] Among wide possibilities of power and torque transmitting devices, the most popular are the devices built with gear trains of various types such as helical, worm and worm wheel, heli-bevel, planetary etc. The other devices being turbo-machinery. Conventionally, all the gearboxes and gear trains mostly use rolling element bearings or alternately plain journal bearings, and both gears and bearings being lubricated by either a forced lubrication or a splash or dip lubrication depending on the applications and various other factors defining the choice.
[003] The drive train is one area of the vehicle where many different sources of losses are found. The gearbox is one example, where the losses are both dependent and independent on the torque transferred by the gear pairs. The gearbox consists of several components that contribute to the total system power loss. Power losses in a gearbox containing several gear pairs that are supported by shafts and rolling element bearing can be classified into two groups. The first group is comprised of load dependent (friction induced) power losses caused primarily due to contacting surfaces of gears and the bearings. The losses in the second group are independent of the load and are often referred to as spin power losses. There are many sources of such losses, the primary one being oil churning and windage that are present as a result of oil/air drag on the periphery and faces of the gears, pocketing/oil squeezing of lubricant from the cavities of the gear mesh and viscous dissipation of the bearing. While losses from these two groups are often comparable under high load, low-speed conditions, the spin losses are shown to dominate over the load dependent power losses at higher operating speed conditions. This problem magnifies non-linearly in case of ultra-high speed enhancers and step-up gear trains. For example, in any transmission involving a gear train specially a speed enhancer, one of the critical limitations to achieve ultra-high speeds is the limitation of the bearings used for the purpose, for example rolling element bearings. The bearings are defined by the DN factor which in turn defines the lubrication to prevent ‘lubricant starvation’ which occurs when bearing speed (N) exceeds the ability of the lubricant to flow back into the bearing track. This phenomenon can be the cause of metal-on-metal contact, which causes rapid wear and necessitates early replacement. Also since the rolling fatigue life of bearing depends greatly upon the viscosity and film thickness between the rolling contact-surface, besides limiting the speeds, needs complex lubrication solutions.
[004] Recent developments of 3rd generation foil air bearings (FABs) to replace rolling element bearings and plain journal bearings have resulted in gearboxes being free from the need of oil lubrication. Though foil air bearings offer exemplary advantages over rolling element bearings in terms of achieving ultra-high speeds, noise elimination, low drag friction, higher load carrying capacities, eliminating the need for oil lubrication, they are challenged with a couple of constraints at start / stop condition as well as at some higher speeds and upwards in absence of cooling. These (FABs) are limited by lower load capacity during start/stop conditions. Initially, the bearing experiences high torque, as the foils rub against the runner surface. As speed is increased, the bearing begins to develop the gas film and the resulting hydrodynamic pressure, decreasing contact and thus the torque. The torque continues to decrease with speed until the gas film is fully developed, at which point the torque is entirely due to shear forces in the thin film. At this point, the torque again increases with speed as the shear forces in the air increase as the speed gradient increases. At higher speeds, the load capacity of foil gas thrust bearings has been found to decrease with speed. This is thought to be a result of a breakdown in thermal management, as the heat generated by the bearing becomes too great to be dissipated in the bearing. Again touchdown during coast down is marked by increased torque, faster deceleration, and increased vibration.
[005] Therefore, there exists a need for a system and a method for pressurized air supply to foil air bearings (FABs) in one of a power transmission device (gearbox) and a turbo-machinery device, which obviates the aforementioned drawbacks.

OBJECTS
[006] The principal object of an embodiment herein is to provide a system and a method for pressurized air supply to foil air bearings in one of a power transmission device (gearbox) and a turbo-machinery device, thereby enhancing the performance of the foil air bearings resulting in enhanced performance of the power transmission device.
[007] Another object of an embodiment herein is to provide a system and a method for both cooling and pressurizing of the foil air bearings (FABs) and enhancing their performance in the deployed gearbox, specifically in an ultra-high speed gearbox in a supercharger application, or a transmission device be it a speed reducer or enhancer used in any other automotive, industrial or aerospace applications.
[008] Another object of an embodiment herein is to enhance performance of the foil air bearings (FABs).
[009] Another object of an embodiment herein is to provide pressurized air to the (FABs) which enables not only higher load carrying capacity during start/stop but also enhanced thermal management during higher speeds because of pressurized cooling effect for better performance of the (FABs).
[0010] Another object of an embodiment herein is to provide side feed pressurization air cooling for FABs, which improves the dynamic performance of the FABs, where it increases direct stiffness, damping and overall stability especially for high speed operation.
[0011] Another object of an embodiment herein is to allow a forced air flow underneath the corrugated bearing structure and the clearance between bearing journal and top foil to dissipate heat generated by the FABs through convection and conduction effects thereby cooling FABs.
[0012] Another object of an embodiment herein is to provide the system and the method of cooling foil air bearings FABs during start/stop conditions thereby enabling hydrodynamic bearings to behave hydrostatic taking advantage of available pressurized air.
[0013] Another object of an embodiment herein is to provide the cooling system for the foil air bearings (FABs), which is reliable and enables effective operability of foil air bearings (FABs).
[0014] Another object of an embodiment herein is to provide provision of pressurized air cooling in the gearbox using the pressure gradient created between input and output of the gearbox for enabling side feed pressurization of Foil Air Bearings which improves the dynamic performance of the FABs.
[0015] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF DRAWINGS
[0016] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0017] Fig. 1 depicts a sectional side view of a typical high speed gearbox in which pressurized air flows to the foil air bearings, according to embodiments as disclosed herein;
[0018] Fig. 2 depicts a sectional view of a typical bump-type Foil air journal bearing that is used in a gearbox or any high load high speed application, according to embodiments as disclosed herein;
[0019] Fig. 3 depicts a sectional view of a typical bump-type Foil air thrust bearing that is used in a gearbox or any high load high speed application, according to embodiments as disclosed herein;
[0020] Fig. 4 depicts a sectional side view and a front view of an air inlet member (front end cover/ input cover flange) of gearbox in which an air inlet port receives pressurized air from an air source, according to embodiments as disclosed herein;
[0021] Fig. 5 depicts a sectional side view and a front view of an air outlet member (rear end cover/ output cover flange) of gearbox in which the air outlet member vents the air to ambient, according to embodiments as disclosed herein;
[0022] Fig. 6 depicts sectional front view of an air flow control mechanism, according to embodiments as disclosed herein;
[0023] Fig. 7 depicts font view of a closure member of the air flow control mechanism, according to embodiments as disclosed herein;
[0024] Fig. 8 depicts a schematic layout of the system for pressurized air supply to the foil air bearings, according to embodiments as disclosed herein;
[0025] Fig. 9 depicts a schematic view of a linear actuator coupled to the closure member of the air flow control mechanism, according to embodiments as disclosed herein; and
[0026] Fig. 10 depicts a flowchart indicating steps of a method for pressurized air supply to the foil air bearings in the power transmission device or turbo-machinery device, according to embodiments as disclosed herein.

DETAILED DESCRIPTION
[0027] 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 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.
[0028] The embodiments herein achieve performance enhancement of Foil Air Bearings (FAB) deployed in a gearbox, which in turn has turned out to be an ‘oil free’ gearbox by virtue of deployment of FABs. The performance enhancement of FABs in turn enhances the efficacy of subject gearbox, more specifically and predominantly in ultra-high speed enhancing gearboxes. The shear saving in the power / energy needed to drive such FAB based transmission device as compared to devices using conventional bearings makes it a very attractive proposition for adoption. The advantage of an oil free highly efficient gearbox finds an instant demand in both current and future critical applications in many market segments such as food industry, pharmaceutical industry and other sector/segment applications where either presence of oil is a maintenance constraint or hindrance to its usage itself. Hence, with the expected massive shift towards adoption of FABs replacing conventional bearings, the need for an effective but economical solution to the current challenges and constraints in usage of FABs attain a prioritized significance. Referring now to the drawings, and more particularly to Figs. 1 through 10, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0029] Foil air bearings (FABs) are based on the hydrodynamic pressure. Viscous drag forces between the moving runner surface and the air and the compliant spring-like structure of the bearing allow and form the film, which supports the bearing load. A journal type FAB as shown in Fig.2 is used on shafts for catering to the radial loads, and a Thrust type FAB as shown in Fig.3 are used for catering to the axial and thrust loads.
[0030] Fig. 1 depicts a sectional side view of a typical high speed power transmission device (100) in which pressurized air flows to the foil air bearings (105, 106), according to embodiments as disclosed herein. An air source is connected in every application to the power transmission device ((100), (gearbox)) at its input end through a specially designed air inlet member ((14), front end cover/ input cover or input flange)) for the purpose. The output side of the power transmission device ((100), (gearbox)) in its air outlet member ((16), rear end cover)) is a specially designed air flow control mechanism (18) for the purpose, which controls the outflow of the air from the power transmission device ((100), (gearbox)). The air at the inlet member (14) is in a pressurized condition and same being at atmospheric level at the air outlet member (16) as it is open to atmosphere or being a vacuum in case of outlet being an inlet of a compressor, forms a natural pressure gradient from input side of the power transmission device ((100), (gearbox)) to output side and creating a forced air directional flow from input to output passing over every element in the power transmission device ((100), (gearbox)) present between input and output sides. With the air flow control mechanism (18) at the output side of the power transmission device ((100), (gearbox)), the pressure inside the gearbox as well as the gradient and directional flow can be controlled. With this mechanism it is made possible in the most cost effective way, the availability of a pressurized air chamber just prior to starting a gearbox i.e just before the foil air bearings FABs (105, 106) incorporated rotating members begin to rotate followed by when they begin to rotate up to a speed when hydrodynamic air film is fully formed. Similarly, while the rotating members begin to decelerate and coast down to halt on account of stopping the gearbox, as well as a free directional air flow during the operation of the gearbox between starting and stopping. This phenomenon solves the problem faced by the Foil Air bearings at all the constrained operating conditions from start to stop. The power transmission device (100) includes, an input shaft 101, a bearing (102), a housing (103), a plurality of foil air bearings (105, 106), a planetary gear train (106) and an output shaft (107).
[0031] Fig. 2 shows a front sectional view of a journal Foil Air bearing FAB (105) used in the embodiments of the invention disclosed herein. FABs are based on the hydrodynamic pressure. This pressure is induced by a generated slip stream between the turning bearing journal, An elastic structure comprises one or more thin top foils (105c) supported by corrugated bumps (105b). The bump is designed so that bump stiffness is much lower than the stiffness of the hydrodynamic gas film and therefore controls the overall stiffness of the bearing. The controlled stiffness leads to the desirable properties of being able to accommodate misalignment, tolerance variation, differential thermal expansion, and centrifugal shaft growth. Therefore an optimal film thickness is achieved and higher loadings are possible. FABs come with practically no speed limitation for operation and their load bearing capacity increasing linearly with speed, provided an effective pressurized cooling is in place, become in terms of technical and commercial feasibility, best suited for the ultra-high speed application, besides any other transmission application.
[0032] Fig. 3 shows a sectional side view of the Thrust Foil Air Bearing FAB (106) in Fig.1, Thrust Foil Air Bearings are used to support axial loads and are made up of three main components. The air outlet member (108) which is the housing of the gearbox GB serves as the base of the bearing. The bump foils (106a) create the spring-like characteristics of the bearing. The top foils (106b) provide a smooth surface for the gas film to develop on to generate hydrodynamic pressure. The surfaces of the top foil (106b), bump foil (106a) and the runner (rotating element) are coated with solid-lubricants to decrease the friction coefficients between surfaces prior to forming the air film. However FABs too come with a few challenges which are mentioned in above paragraphs. The above mentioned challenges for the FABs adopted in the disclosed embodiments of the current invention, can be effectively addressed by timely providing pressurized air which would enable not only higher load carrying capacity during start/stop but also enhanced thermal management because of pressurized cooling effect for better performance.
[0033] Fig. 8 depicts a schematic layout of the system (10) for pressurized air supply to the foil air bearings (105, 106), according to embodiments as disclosed herein. The system (10) includes an air source (12), an air inlet member (14), an air outlet member (16), an air flow control mechanism (18), a plurality of springs (20), a pressure relief valve ((22), (as shown in fig. 1)), a controller unit (24), a pressure sensor (26), a temperature sensor (28) and a speed sensor (30). For the purpose of this description and ease of understanding, the system (10) is explained herein below with reference to pressurized air supply to foil air bearings (105, 106) in a power transmission device (100) or turbo-machinery device. However, it is also within the scope of the invention to practice/ use the elements/components of the system (10) for pressurized air supply to foil air bearings used in any other applications, without otherwise deterring the intended function of the pressurized air supply system (10) as can be deduced from the description and corresponding drawings. The foil air bearings (105, 106) are located inside the housing (103) of one of the power transmission device (100) and the turbo-machinery device.
[0034] In one embodiment, the air source (12) is considered to be an air pump. In another embodiment, the air source (12) is considered to be high pressure line of the supercharging/boosting system or pre-generated pneumatic high pressure line for any other purpose such as air brakes in an automotive applications or high pressure pneumatic line in an industry, whereas the high pressure line may require control valves for controlling air flow to the air inlet member (14).
[0035] The air inlet member (14) has at least one air inlet port (14A) and a plurality of air outlet ports (14B). The air inlet port (14A) of the air inlet member (14) is in pressurized air communication with the air source (12) and the air outlet ports (14B). The air inlet member (14) includes at least one air flow gallery (14C) adapted to allow pressurized air flow from the air inlet port (14A) to the air outlet ports (14B) of the air inlet member (14). The air outlet ports (14B) of the air inlet member (14) are adapted to allow pressurized air flow to the foil air bearings (105, 106). For the purpose of this description and ease of understanding, each air outlet port (14B) of the air inlet member (14) is a conical shaped air outlet port. The air outlet ports (14B) of the air inlet member (14) enables the pressurized air to expand into the housing (103) of power transmission device (100) with which the pressure drops and consequently temperature, but pressure in the expanded chamber of the housing (103) is always retained at levels above ambient pressure. It is also within the scope of the invention to provide the air outlet ports (14B) of the air inlet member (14) in any other shape but the opening of the air outlet port (14B) should be tapered away from the air flow gallery (14C). The pressurized air is adapted to enhance the operating efficiency of the foil air bearings (105, 106) and to cool the foil air bearings (105, 106). For the purpose of this description and ease of understanding, air inlet member (12) is a front end cover (input cover flange) of a power transmission device (10). In another embodiment, the system (10) may include nozzles located inside or fitted to the housing (103) for delivering pressurized air flow to the foil air bearings. Further, the housing (103) can be provided with embedded ducting in the body of the housing (103) for high pressure air to flow through and exit to the inside chamber through conical air outlet ports positioned anywhere between input and output sides of the power transmission device (100) at various distances from input to ensure availability of pressurized air at various sections of the chamber for effective pressurization and cooling of the FABs. Furthermore, in another embodiment, the air inlets can be provided on the housing (103) for providing pressurized air flow to the foil air bearings (105, 106). The air outlet member (16) has a plurality of air outlet ports (16A). For the purpose of this description and ease of understanding, the air outlet member (16) is considered to be a rear end cover (output cover flange) of the power transmission device (10).
[0036] Fig. 6 depicts sectional front view of an air flow control mechanism (18), according to embodiments as disclosed herein. The air flow control mechanism (18) includes an intermediate air outlet member (18A) and a closure member ((18B), (as shown in fig. 6 and fig. 7). The intermediate air outlet member (18A) is mounted onto the air outlet member (16) and is engaged with the housing (103). The intermediate air outlet member (18A) defines a plurality of air orifices (18AP). For the purpose of this description and ease of understanding, each air orifice (18AP) of the intermediate air outlet member (18A) is a conical shaped air orifice. The closure member (18B) is adapted to be moved between one of an engaged position and a disengaged position with respect to the intermediate air outlet member (18A). The closure member (18B) is engaged with the intermediate air outlet member (18A) in the engaged position thereby blocking the air orifices (18AP) to retain the pressurized air within a housing (103) so that the pressurized air flows to the foil air bearings (105, 106) until the closure member (18B) is moved to the disengaged position. The closure member (18B) is disengaged from the intermediate air outlet member (18A) in the dis-engaged position thereby allowing the pressurized air flow to the air outlet ports (16A) of the air outlet member (16) via the air orifices (18AP) of the intermediate air outlet member (18A), and accordingly the air outlets ports (16A) of the air outlet member (16) vents the air.
[0037] Initially with the closure member (18B) butting airtight with face of intermediate air outlet member (18A), the air orifices (18AP) are in closed position. With continuing and increasing inflow of the external pressurized air from air inlet port (14A) of the air inlet member (14) and the pre-pressurized air being retained in the chamber of the housing (103) due to closed air orifices (18AP) of the intermediate air outlet member (18A), the pressure in the chamber of the housing (103) increases further. Pressurized air acting on the closure member (18B) via the plurality of air orifices (18AP) apply force on the surface of closure member (18B), and when the collective force exceeds the combined retaining force of the springs (20), the closure member (18B) is pushed back to create gap between the intermediate air outlet member (18A) and the closure member (18B) for the pressurized air to flow out through the air outlet ports (16A) defined on the air outlet member (16). Since the air outlet ports (16A) defined on the air outlet member (16) is connected to open air with atmospheric pressure or in other cases being connected to the inlet of a compressor where vacuum prevails, the flow is further accelerated. With outflow of air, pressure in the chamber of the housing (103) drops. As the pressure drops further until the collective force of air pressure acting on the closure member (18B) via the air orifices (18AP) of the intermediate air outlet member (18A) falls below the combined tensile force of the springs (20), the closure member (18B) withdraws and butts airtight against intermediate air outlet member (18A), closing the air orifices (18AP) and blocking the flow of air, thereby building pressure in the chamber of the housing (103) again, this process operates in a cyclic way until supply of pressurized air at air inlet port (14A) is stopped. Through such a method, cooled air streaming underneath the corrugated bearing structure and the clearance between bearing journal and top foil of the FABs a forced cooling flow is achieved where heat is transported by convection and conduction effects, thereby ensuring enhanced performance of FABs and leading to a trouble free operation of the oil free power transmission device (100, gearbox). The flow control mechanism (18) explained above enables a pressurized environment for FABs just prior to and during starting as well as at the time of stopping and slightly after stopping condition specifically solves the problem faced by FABs at start/stop conditions mentioned above, thereby further enabling the power transmission device (100, gearbox) with FABs being oil free and highly efficient under wider operating conditions.
[0038] The plurality of springs (20) adapted to movably connect the closure member (18B) to the intermediate air outlet member (18A). One end of the spring (20) is connected to the intermediate air outlet member (18A) and another end of the spring (20) is connected to the closure member (18B). The closure member (18B) is adapted to move from the engaged position to the disengaged position (as shown in fig. 6) when the pressure of air in the housing (103) is more than the collective tensile force of the springs (20). The closure member (18B) is adapted to move from the disengaged position to the engaged position (as shown in fig. 6) when the pressure of air in the housing (103) is less than the collective tensile force of the springs (20).
[0039] The pressure relief valve (22) is located on the housing (103). The pressure relief valve (22) is adapted to vent the pressurized air when the pressure of air in the housing (12) exceed a preset relief pressure of the pressure relief valve (22).
[0040] The pressure sensor (26) is adapted to measure and communicate pressure of air in the housing (103) to the controller unit (24). The temperature sensor (28) is adapted to measure and communicate temperature of air in the housing (103) to the controller unit (24). The speed sensor (30) is adapted to measure and communicate speed of an output member (107) of the power transmission device (100) or turbo-machinery device to the controller unit (24). The controller unit (24) is configured to operate the air source (12) which in turn at least one of, supply, cut-off and regulate pressurized air flow to the air inlet port (14A) of the air inlet member (14) respectively based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). In an embodiment, the air source (12) is considered to be an air pump.
[0041] In another embodiment, the system (10) includes a main control valve (32), an accumulator (34) and a non-return valve ((36), (as shown in fig. 8), if the air source (12) is a pressurized pneumatic line. The system (10) provide pressurized air ambience to the FABs just before the FABs are subjected to start or operate and up to a small duration after the gearbox is stopped and FABs have come to halt, and continuous cooling through pressurized air during continuous operation of the gearbox between starting and stopping. The main control valve (32) is in communication with the controller unit (24). The main control valve (32) is adapted to operatively connect the air source (12) in pressurized air communication with the air inlet port (14A) of the air inlet member (14). The controller unit (24) is configured to operate the main control valve (32) to at least one of supply, cut-off and regulate pressurized air flow from the air source (12) to the air inlet port (14A) of the air inlet member (14) respectively through the main control valve (32) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30).
[0042] The accumulator (34) is adapted to be operatively in pressurized air communication with the main control valve (32). The non-return valve (36) in pressurized air communication with the air source (12). The non-return valve (36) is adapted to restrict pressurized air flow from the accumulator (34) to air source (12). The controller unit (24) is configured to operate the main control valve (32) to supply or cut-off or regulate pressurized air flow from the accumulator (34) to the air inlet port (14A) of the air inlet member (14) respectively through the main control valve (32) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). In all the above mentioned case, only after the housing (103) of power transmission device 100 is pressurized with air at a pre-determined pressure, the controller 24 switches on the motor or engine to drive the power transmission device 100. By doing so the FABs at starting condition are subjected to pressurized air and can operate as hydrostatic bearing until the speed at which a hydrodynamic phenomenon gets operational. Similarly, the Controller 24 at the stopping condition of the power transmission device 100, once the motor 210 is switched off or clutch disengaged, the drive shafts of the power transmission device 100 may continue to spin or may stop. In any case, the controller 24 only after a small duration after it receives the signal of speed sensor (30) that the speed is equal to zero, sends a signal to the main control valve (32) in pressurized input line or to the air pump 12 to stop supplying, thereby ensuring the FABs have decelerated and come to halt in the presence/ ambience of pressurized air. During the operation of the gearbox in between starting and stopping, the accumulator 34, if discharged, is recharged to be ready for discharging at the beginning of the next cycle or to intermittently fill for leakages if any. The functioning of the pressurized sir supply system along with cooling of FABs during the operational phase of the power transmission device (gearbox) between starting and before stopping is more fully explained in the previous sections above. This pressurized air supply system also caters to the cooling of all other rotating members such as gears and shafts in the power transmission device (gearbox). Thus the air cooling system operates to ensure a fail proof mechanism for the FABs. This in turn results in FABs being highly efficient which make them to be high performance, energy/fuel saving augmenters in any system involving their deployment as in case of a power transmission device (gearbox) explained above.
[0043] In an embodiment, the controller (24) in sends a signal to main control device (32) to open the corresponding port for the air source (12) to supply air to the air inlet member (14) of the power transmission device (100), and the controller unit (24) may also additionally send a signal to the main control device (32) to open the discharge port of accumulator (34) to allow pressurized air flow to the air inlet member (14) for accelerating the pressure buildup in the power transmission device (100), (gearbox). The design capacity of accumulator (34) in each case corresponds to capacity required to charge the subject gearbox and generate pressure even in absence of any other source of pressurized line.
[0044] Fig. 9 depicts a schematic view of a linear actuator (21) coupled to the closure member (18B) of the air flow control mechanism (18), according to embodiments as disclosed herein. In another embodiment, the system (10) includes at least one linear actuator (21) in communication with the controller unit (24), wherein the linear actuator (21) includes a final linearly movable member (21L) adapted to be connected to the closure member (18B). The linearly movable member (21L) of the linear actuator (21) is adapted to move the closure member (18B) to one of the engaged position and dis-engaged position based on the signal from said controller unit (24) to the linear actuator (21) in accordance to the signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30).
[0045] Fig. 10 depicts a flowchart indicating steps of a method (700) for pressurized air supply to the foil air bearings (105, 106) in the power transmission device (100) or turbo-machinery device, according to embodiments as disclosed herein. For the purpose of this description and ease of understanding, the method (700) is explained herein with below reference to pressurized air supply to foil air bearings (105, 106) in a power transmission device (100) or turbo-machinery device. However, it is also within the scope of this invention to practice/implement the entire steps of the method (700) in a same manner or in a different manner or with omission of at least one step to the method (700) or with any addition of at least one step to the method (700) for pressurized air supply to foil air bearings used in any other applications, without otherwise deterring the intended function of the method (700) as can be deduced from the description and corresponding drawings. At step (702), the method (700) includes, allowing, by an air source (12), pressurized air flow to at least one air inlet port (14A) defined on an air inlet member (14). At step (704), the method (700) includes, allowing, by the at least one air inlet port (14A) of the air inlet member (14), the pressurized air flow to a plurality of air outlet ports (14B) defined on the air inlet member (14). At step (706), the method (700) includes, allowing, by the air outlet ports (14B) of the air inlet member (14), the pressurized air flow to the foil air bearings (B) located inside a housing (103) of the power transmission device (100) or the turbo-machinery device. At step (708), the method (700) includes, blocking, by a closure member (18B) of an air flow control mechanism (18), a plurality of air orifices (18AP) defined on an intermediate air outlet member (18A) by maintaining the closure member (18B) engaged with the intermediate air outlet member (18A) thereby retaining the pressurized air within the housing (103) so that the pressurized air flows to the foil air bearings (105, 106) until the closure member (18B) is disengaged from the intermediate air outlet member (18A). At step (710), the method (700) includes, allowing, by air orifices (18AP) of the intermediate air outlet member (18A), the pressurized air flow to a plurality of air outlet ports (16A) defined on an air outlet member (16) in response to moving the closure member (18B) from an engaged position to a disengaged position in which the closure member (18B) is disengaged from the intermediate air outlet member (18A). At step (712), the method (700) includes, venting the air by the air outlets ports (16A) of air outlet member (16). Further, the method (700) includes, moving, by the pressurized air, the closure member (18B) from the engaged position to the disengaged position when the pressure of air in the housing (103) is more than a tensile force of springs (20). Further, the method (700) includes, moving, by the springs (20), the closure member (18B) from the disengaged position to the engaged position when the pressure of air in the housing (103) is less than the tensile force of the springs (20). Furthermore, the method (700) includes, measuring and communicating, by a pressure sensor (26), a pressure of air in the housing (103) to a controller unit (24). The method (700) includes, measuring and communicating, by a temperature sensor (28), a temperature of air in the housing (103) to the controller unit (24). The method (700) includes, measuring and communicating, by a speed sensor (30), a speed of an output member (107) of the power transmission device (100) or turbo-machinery device to the controller unit (24). Further, the method (700) includes, operating, by the controller unit (24), the air source (12) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). Furthermore, the method (700) includes, supplying or regulating or cutting-off, by the air source (12), pressurized air flow to the air inlet port (14A) of the air inlet member (14) respectively in response to said operating the air source (12) by the controller unit (24) based on the signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30).
[0046] In another embodiment, the method (700) includes, operating, by the controller unit (24), a main control valve (32) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). Further, the method (700) includes, supplying or regulating or cutting-off, by the main control valve (32), pressurized air flow from the air source (12) to the air inlet port (14A) of the air inlet member (14) in response to said operating the main control valve (32) by the controller unit (24) based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30). Furthermore, the method (700) includes, supplying or regulating or cutting-off, by the main control valve (32), pressurized air flow from an accumulator (34) to the air inlet port (14A) of the air inlet member (14) in response to said operating the main control valve (32) by the controller unit (24) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). Further, the method (700) includes, blocking, by a non-return valve (36), pressurized air flow from the accumulator (34) to the air source (12) through the main control valve (32).
[0047] In another embodiment, the method (700) includes, operating, by the controller unit (24), at least one linear actuator (21) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). Furthermore, the method (700) includes, moving, by a linearly movable member (21L) of the linear actuator (21), the closure member (18B) with respect to the intermediate air outlet member (18A) to one of the engaged position and dis-engaged position in response to operating the linear actuator (21) by the controller unit (24) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30). The method (700) includes, venting, by a pressure relief valve (22) located on the housing (103) when the pressure of air in the housing (12) exceed a preset relief pressure of the pressure relief valve (22).
[0048] The technical advantages of the pressurized air supply system (10) are as follows. Enhance performance of the foil air bearings (FABs) thereby enhancing performance of the power transmission device/ turbo-machinery device. Cooling and pressurizing of the foil air bearings (FABs) and enhancing their performance in the deployed gearbox, specifically in an ultra-high speed gearbox in a supercharger application, or a transmission device be it a speed reducer or enhancer used in any other automotive, industrial or aerospace applications. Providing pressurized air to the (FABs) which enables not only higher load carrying capacity during start/stop but also enhanced thermal management because of pressurized cooling effect for better performance of the (FABs). Side feed pressurization air cooling for FABs, which improves the dynamic performance of the FABs, where it increases direct stiffness, damping and overall stability especially for high speed operation. Cooling the foil air bearings FABs during start/stop conditions thereby enabling hydrodynamic bearings to behave hydrostatic taking advantage of available pressurized air. Allowing a forced air flow underneath the corrugated bearing structure and the clearance between bearing journal and top foil to dissipate heat generated by the FABs through convection and conduction effects thereby cooling FABs. Providing provision of pressurized air cooling in the gearbox using the pressure gradient created between input and output of the gearbox for enabling side feed pressurization of Foil Air Bearings which improves the dynamic performance of the FABs.
[0049] 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 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 embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:We claim,

1. A system (10) for pressurized air supply to foil air bearings (105, 106) in a power transmission device (100) or turbo-machinery device, said system (10) comprising:
an air source (12);
an air inlet member (14) having at least one air inlet port (14A) and a plurality of air outlet ports (14B), wherein said air inlet port (14A) is in pressurized air communication with said air source (12) and said air outlet ports (14B), wherein said air outlet ports (14B) is adapted to allow pressurized air flow to the foil air bearings (105, 106);
an air outlet member (16) having a plurality of air outlet ports (16A);
an air flow control mechanism (18), said air flow control mechanism (18) includes an intermediate air outlet member (18A) and a closure member (18B), where said intermediate air outlet member (18A) defines a plurality of air orifices (18AP), wherein said closure member (18B) is adapted to be moved between one of an engaged position and a disengaged position with respect to said intermediate air outlet member (18A).
2. The system (10) as claimed in claim 1, wherein said closure member (18B) is engaged with said intermediate air outlet member (18A) in said engaged position thereby blocking said air orifices (18AP) to retain the pressurized air within a housing (103) so that the pressurized air flows to the foil air bearings (105, 106) until said closure member (18B) is moved to said disengaged position; and
said closure member (18B) is disengaged from said intermediate air outlet member (18A) in said dis-engaged position thereby allowing the pressurized air flow to said air outlet ports (16A) of said air outlet member (16) via said air orifices (18AP) of said intermediate air outlet member (18A), and accordingly said air outlets ports (16A) of said air outlet member (16) vents the air;
said intermediate air outlet member (18A) is mounted onto said air outlet member (16) and is engaged with the housing (103); and
the foil air bearings (105, 106) are located inside the housing (103) of one of the power transmission device (100) and a turbo-machinery device.
3. The system (10) as claimed in claim 1, wherein said system (10) includes a plurality of springs (20) adapted to movably connect said closure member (18B) to said intermediate air outlet member (18A), where one end of said spring (20) is connected to said intermediate air outlet member (18A) and another end of said spring (20) is connected to said closure member (18B),
wherein
said closure member (18B) is adapted to move from the engaged position to the disengaged position when the pressure of air in the housing (103) is more than the collective tensile force of said springs (20); and
said closure member (18B) is adapted to move from the disengaged position to the engaged position when the pressure of air in the housing (103) is less than the collective tensile force of said springs (20).
4. The system (10) as claimed in claim 1, wherein said system (10) includes,
a controller unit (24);
a pressure sensor (26) adapted to measure and communicate pressure of air in the housing (103) to said controller unit (24);
a temperature sensor (28) adapted to measure and communicate temperature of air in the housing (103) to said controller unit (24); and
a speed sensor (30) adapted to measure and communicate speed of an output member (107) of the power transmission device (100) or turbo-machinery device to said controller unit (24).
5. The system (10) as claimed in claim 4, wherein said controller unit (24) is configured to operate said air source (12) which in turn at least one of supply, cut-off and regulate pressurized air flow to said air inlet port (14A) of said air inlet member (14) respectively based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30),
wherein
said air source (12) is at least an air pump.
6. The system (10) as claimed in claim 4, wherein said system (10) includes,
a main control valve (32) in communication with said controller unit (24), said main control valve (32) is adapted to operatively connect said air source (12) in pressurized air communication with said air inlet port (14A) of said air inlet member (14),
wherein
said controller unit (24) is configured to operate said main control valve (32) to at least one f supply, cut-off and regulate pressurized air flow from said air source (12) to said air inlet port (14A) of said air inlet member (14) respectively through said main control valve (32) based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30); and
said air source (12) is a pressurized pneumatic line.
7. The system (10) as claimed in claim 6, wherein said system (10) includes,
an accumulator (34) adapted to be operatively in pressurized air communication with said main control valve (32); and
a non-return valve (36) in pressurized air communication with said air source (12),
wherein
said controller unit (24) is configured to operate said main control valve (32) to at least one of supply, cut-off and regulate pressurized air flow from said accumulator (34) to said air inlet port (14A) of said air inlet member (14) respectively through said main control valve (32) based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30); and
said non-return valve (36) is adapted to restrict pressurized air flow from said accumulator (34) to air source (12).
8. The system (10) as claimed in claim 4, wherein said system (10) includes at least one linear actuator (21) in communication with said controller unit (24), wherein said linear actuator (21) includes a final linearly movable member (21L) adapted to be connected to said closure member (18B),
wherein
said linearly movable member (21L) of said linear actuator (21) is adapted to move said closure member (18B) to one of said engaged position and dis-engaged position based on the signal from said controller unit (24) to said linear actuator (21) in accordance to the signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30).
9. The system (10) as claimed in claim 2, wherein said system (100) includes a pressure relief valve (22) located on the housing (103), wherein said pressure relief valve (22) is adapted to vent the pressurized air when the pressure of air in the housing (12) exceed a preset relief pressure of said pressure relief valve (22).
10. The system (10) as claimed in claim 1, wherein said air inlet member (14) includes at least one air flow gallery (14C) adapted to allow pressurized air flow from said air inlet port (14A) to said air outlet ports (14B) of said air inlet member (14);
each of said air outlet port (14B) of said air inlet member (14) is a conical shaped air outlet port;
each of said air orifice (18AP) of said intermediate air outlet member (18A) is a conical shaped air orifice;
said pressurized air is adapted to enhance the operating efficiency of the foil air bearings (105, 106) and to cool the foil air bearings (105, 106);
said air inlet member (14) is a front end cover of a power transmission device (10); and
said air outlet member (16) is a rear end cover of the power transmission device (10).
11. A method (700) of pressurized air supply to foil air bearings (16) in a power transmission device (100) or turbo-machinery device, said method (700) comprising:
allowing, by an air source (12), pressurized air flow to at least one air inlet port (14A) defined on an air inlet member (14);
allowing, by the at least one air inlet port (14A) of the air inlet member (14), the pressurized air flow to a plurality of air outlet ports (14B) defined on the air inlet member (14);
allowing, by the air outlet ports (14B) of the air inlet member (14), the pressurized air flow to the foil air bearings (B) located inside a housing (103) of the power transmission device (100) or the turbo-machinery device; and
blocking, by a closure member (18B) of an air flow control mechanism (18), a plurality of air orifices (18AP) defined on an intermediate air outlet member (18A) by maintaining the closure member (18B) engaged with the intermediate air outlet member (18A) thereby retaining the pressurized air within the housing (103) so that the pressurized air flows to the foil air bearings (105, 106) until the closure member (18B) is disengaged from the intermediate air outlet member (18A).
12. The method (700) as claimed in claim 11, wherein said method (700) includes,
allowing, by air orifices (18AP) of the intermediate air outlet member (18A), the pressurized air flow to a plurality of air outlet ports (16A) defied on an air outlet member (16) in response to moving the closure member (18B) from an engaged position to a disengaged position in which the closure member (18B) is disengaged from the intermediate air outlet member (18A); and
venting the air by the air outlets ports (16A) of air outlet member (16).
13. The method (700) as claimed in claim 11, wherein said method (700) includes,
moving, by the pressurized air, the closure member (18B) from the engaged position to the disengaged position when the pressure of air in the housing (103) is more than the collective tensile force of springs (20); and
moving, by the springs (20), the closure member (18B) from the disengaged position to the engaged position when the pressure of air in the housing (103) is less than the collective tensile force of the springs (20).
14. The method (700) as claimed in claim 11, wherein said method (700) includes,
measuring and communicating, by a pressure sensor (26), a pressure of air in the housing (103) to a controller unit (24);
measuring and communicating, by a temperature sensor (28), a temperature of air in the housing (103) to the controller unit (24);
measuring and communicating, by a speed sensor (30), a speed of an output member (107) of the power transmission device (100) or turbo-machinery device to the controller unit (24).
15. The method (700) as claimed in claim 14, wherein said method (700) includes,
operating, by the controller unit (24), the air source (12) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30); and
supplying or regulating or cutting-off, by the air source (12), pressurized air flow to the air inlet port (14A) of the air inlet member (14) respectively in response to said operating the air source (12) by the controller unit (24) based on the signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30),
wherein
the air source (12) is at least an air pump.
16. The method (700) as claimed in claim 14, wherein said method (700) includes,
operating, by the controller unit (24), a main control valve (32) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30); and
supplying or regulating or cutting-off, by the main control valve (32), pressurized air flow from the air source (12) to the air inlet port (14A) of the air inlet member (14) in response to said operating the main control valve (32) by the controller unit (24) based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30),
wherein
the air source (12) is a pressurized pneumatic line.
17. The method (700) as claimed in claim 16, wherein said method (700) includes,
supplying or regulating or cutting-off, by the main control valve (32), pressurized air flow from an accumulator (34) to the air inlet port (14A) of the air inlet member (14) in response to said operating the main control valve (32) by the controller unit (24) based on signals from at least one of said pressure sensor (26), said temperature sensor (28) and said speed sensor (30); and
blocking, by a non-return valve (36), pressurized air flow from the accumulator (34) to the air source (12).
18. The method (700) as claimed in claim 14, wherein said method (700) includes,
operating, by the controller unit (24), at least one linear actuator (21) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30); and
moving, by a linearly movable member (21L) of the linear actuator (21), the closure member (18B) with respect to the intermediate air outlet member (18A) to one of the engaged position and dis-engaged position in response to operating the linear actuator (21) by the controller unit (24) based on signals from at least one of the pressure sensor (26), the temperature sensor (28) and the speed sensor (30).
19. The method (700) as claimed in claim 11, wherein said method (200) includes,
venting, by a pressure relief valve (22) located on the housing (103) when the pressure of air in the housing (12) exceed a preset relief pressure of the pressure relief valve (22).