AUXILIARY OIL DISTRIBUTION SYSTEM AND GAS TURBINE ENGINE WITH AN AUXILIARY OIL DISTRIBUTION SYSTEM

Abstract

An auxiliary oil distribution system of a geared turbofan engine, with at least one part of the oil transport device driveably connected with at least one rotating part of an epicyclic gearbox of the geared turbofan engine, at least one oil guiding device to collect oil in the gearbox and/or outside the gearbox and to direct the oil to an oil target location.

Claims

1. An auxiliary oil distribution system of a geared turbofan engine, with at least one part of the oil transport device driveably connected with at least one rotating part of an epicyclic gearbox of the geared turbofan engine, at least one oil guiding device to collect oil in the gearbox and/or outside the gearbox and to direct the oil to an oil target location.

2. The auxiliary oil distribution system, according to claim 1, wherein the oil guiding device comprises at least one scoop device and/or at least one oil channel to direct an oil flow to the oil target location.

3. The auxiliary oil distribution system, according to claim 1, wherein the at least one rotating part is a sun gear, a planet carrier or a ring gear of the epicyclic gearbox driveably connected to the oil transport device so that it rotates with the same rotational speed as the rotating device.

4. The auxiliary oil distribution system, according to claim 1, wherein the driving force of the oil in the at least one oil transport device is a pressure difference and/or a centrifugal force generated through the rotating part acting on the oil transport device.

5. The auxiliary oil distribution system, according to claim 1, wherein at least one part of the oil transport device is connected to a static part of the epicyclic gearbox, in particular the planet carrier, the ring gear or the sun gear.

6. The auxiliary oil distribution system according to claim 1, wherein the oil transport device comprises a plurality of epicyclic pump wheels in oil cavities, the pump wheels being driveably connected to the oil transport device for transporting oil towards the target location.

7. The auxiliary oil distribution system according to claim 6, wherein the epicyclic pump wheels in an outer ring of the oil transport device mesh with a toothed rack circumferentially mounted on an inner ring of the oil transport device, the inner ring fastened to planet carrier of the epicyclic gearbox as rotating part, the epicyclic pump wheels preceding around the inner ring, the inner ring being static relative to the outer ring.

8. The auxiliary oil distribution system according to claim 6, wherein the epicyclic pump wheels in an outer ring of the oil transport device mesh with a toothed rack circumferentially mounted on an inner ring of the oil transport device, the inner ring fastened to a static part of the gearbox, the outer ring being driveably connected with the rotating part, in particular the planet carrier, the pump wheels preceding around the inner ring.

9. The auxiliary oil distribution system according to claim 6, wherein the epicyclic pump wheels in an outer ring of the oil transport device mesh with a toothed rack circumferentially mounted at the inside of an outer rim of the oil transport device, a housing of the epicyclic pump wheels being driveably connected with the rotating part, in particular the planet carrier, the epicyclic pump wheels preceding around the toothed rack.

10. The auxiliary oil distribution system according to claim 1, wherein the oil distribution device housing the epicyclic pump wheels in the oil cavities has a flat ring-like or flat plate shape.

11. The auxiliary oil distribution system according to claim 1, wherein the target location is at the gearbox.

12. The auxiliary oil distribution system according to claim 11, wherein the target location comprises a journal bearing, in particular of the planet carrier.

13. The auxiliary oil distribution system according to claim 1, wherein the epicyclic gearbox is in planetary or star configuration.

14. A gas turbine engine for an aircraft comprising: an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan comprising a plurality of fan blades; and a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, with an auxiliary oil distribution system according to claim 1.

Description

[0049] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0050] FIG. 1 is a sectional side view of a gas turbine engine;

[0051] FIG. 2 is a close up sectional side view of an upstream portion of a gas turbine engine;

[0052] FIG. 3 is a partially cut-away view of a gearbox for a gas turbine engine;

[0053] FIG. 4A shows a frontal view of an oil transporting device of a first embodiment of an auxiliary oil distribution system driveably connectable to a carrier of an epicyclic gearbox;

[0054] FIG. 4B shows a sectional view as indicated by A-A in FIG. 4A;

[0055] FIG. 5A shows a perspective cut-away view of a gearbox with the first embodiment of an auxiliary oil distribution system;

[0056] FIG. 5B shows an enlarged section of FIG. 5A;

[0057] FIG. 6A shows a frontal view of an oil transporting device of a second embodiment of an auxiliary oil distribution system driveably connectable to a carrier of an epicyclic gearbox;

[0058] FIG. 6B shows a sectional view as indicated by A-A in FIG. 6A;

[0059] FIG. 7A shows a frontal view of an oil transporting device of a third embodiment of an auxiliary oil distribution system driveably connectable to a carrier of an epicyclic gearbox;

[0060] FIG. 7B shows a sectional view as indicated by A-A in FIG. 7A;

[0061] FIG. 8A shows a perspective cut-away view of a gearbox with the third embodiment of an auxiliary oil distribution system;

[0062] FIG. 8B shows an enlarged section of FIG. 8A.

[0063] FIG. 1 illustrates a gas turbine engine 10 having a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic gearbox 30.

[0064] In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 generally provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

[0065] An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 2. The low pressure turbine 19 (see FIG. 1) drives the shaft 26, which is coupled to a sun wheel, or sun gear, 28 of the epicyclic gear arrangement 30. Radially outwardly of the sun gear 28 and intermeshing therewith is a plurality of planet gears 32 that are coupled together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to precess around the sun gear 28 in synchronicity whilst enabling each planet gear 32 to rotate about its own axis. The planet carrier 34 is coupled via linkages 36 to the fan 23 in order to drive its rotation about the engine axis 9. Radially outwardly of the planet gears 32 and intermeshing therewith is an annulus or ring gear 38 that is coupled, via linkages 40, to a stationary supporting structure 24.

[0066] Note that the terms low pressure turbine and low pressure compressor as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan 23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft 26 with the lowest rotational speed in the engine (i.e. not including the gearbox output shaft that drives the fan 23). In some literature, the low pressure turbine and low pressure compressor referred to herein may alternatively be known as the intermediate pressure turbine and intermediate pressure compressor. Where such alternative nomenclature is used, the fan 23 may be referred to as a first, or lowest pressure, compression stage.

[0067] The epicyclic gearbox 30 is shown by way of example in greater detail in FIG. 3. Each of the sun gear 28, planet gears 32 and ring gear 38 comprise teeth about their periphery to intermesh with the other gears. However, for clarity only, exemplary portions of the teeth are illustrated in FIG. 3. There are four planet gears 32 illustrated, although it will be apparent to the skilled reader that more or fewer planet gears 32 may be provided within the scope of the claimed invention. Practical applications of a planetary epicyclic gearbox 30 generally comprise at least three planet gears 32.

[0068] The epicyclic gearbox 30 illustrated by way of example in FIGS. 2 and 3 is of the planetary type, in that the planet carrier 34 is coupled to an output shaft via linkages 36, with the ring gear 38 fixed. However, any other suitable type of epicyclic gearbox 30 may be used. By way of further example, the epicyclic gearbox 30 may be a star arrangement, in which the planet carrier 34 is held fixed, with the ring (or annulus) gear 38 allowed to rotate. In such an arrangement the fan 23 is driven by the ring gear 38. By way of further alternative example, the gearbox 30 may be a differential gearbox in which the ring gear 38 and the planet carrier 34 are both allowed to rotate.

[0069] It will be appreciated that the arrangement shown in FIGS. 2 and 3 is by way of example only, and various alternatives are within the scope of the present disclosure. Purely by way of example, any suitable arrangement may be used for locating the gearbox 30 in the engine 10 and/or for connecting the gearbox 30 to the engine 10. By way of further example, the connections (such as the linkages 36, 40 in the FIG. 2 example) between the gearbox 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement of FIG. 2. For example, where the gearbox 30 has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing locations would typically be different to that shown by way of example in FIG. 2.

[0070] Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations.

[0071] Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor).

[0072] Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 20, 22 meaning that the flow through the bypass duct 22 has its own nozzle that is separate to and radially outside the core engine nozzle 20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine 10 may not comprise a gearbox 30.

[0073] The geometry of the gas turbine engine 10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the rotational axis 9), a radial direction (in the bottom-to-top direction in FIG. 1), and a circumferential direction (perpendicular to the page in the FIG. 1 view). The axial, radial and circumferential directions are mutually perpendicular.

[0074] The distribution of oil in connection of the gearbox 30 is of great importance to the functionality of the overall gas turbine engine 10. In case of a malfunction, an oil distribution needs to be maintained. This is the purpose of an auxiliary oil distribution system (auxiliary oil pump). Several embodiments for an auxiliary oil distribution system will be described in the following.

[0075] In FIGS. 4A, 4B, 5A, and 5B a first embodiment is shown. In this embodiment the energy to transport the oil (oil flow O in FIG. 4B) to a target location 60 isat least in partgenerated by the rotational movement of the planet carrier 36 (see FIGS. 2 and 3).

[0076] The planet carrier 36 is best seen in FIG. 5A. At the distal end of the carrier 36 an oil transport device 50 is coaxially mounted. The oil transport device 50 is essentially a ring-shaped device, the outer contour in a frontal viewas seen in FIG. 4Ais essentially triangular.

[0077] An inner ring 55 of the oil transport device 50 is rigidly fastened to the planet carrier 36. An outer ring 56 of the oil transport device 50 can rotate around the inner ring 55 (FIG. 4B). At the outer rim of the inner ring 55 a toothed rack is positioned which meshes with pump wheels 53 housed in cavities 57 (see FIG. 4A) within the oil transport device 50.

[0078] Since the planet carrier 36 rotates in operation of the engine 10, the rotation is transmitted via the toothed rack on the inner ring 55 to the pump wheels 53. The outer ring 56 of the oil transport device 50 rotates with the same rotational speed as the planet carrier 34. The motion of the oil transport device 50 is transmitted through an interference spigot with the carrier 36. The pump wheels 53 rotate with the outer ring 56 well as around their own axis meshing with the inner ring 55.

[0079] Oil within a gearbox housing 41 (FIGS. 5A, 5B) is transported towards a target location 60, e.g. a journal bearing in the planet carrier 36, the journal bearing not shown in FIGS. 5A, 5B.

[0080] The oil flow is directedreferring in FIG. 5Bfrom the front to the rear, i.e. directed towards the planet carrier 36.

[0081] The oil flow O is best seen in FIG. 4B which is a cut section of FIG. 4A.

[0082] In the corners of the oil transport device 50 the pump wheels 53 are mounted, meshing with the circumferential toothed rack of the inner ring 55. One of the pump wheels 53 is seen in the cut section of FIGS. 4B and 5B.

[0083] The rotation of the outer ring 56 of the oil transport device 50 causes the pump wheels 53 to rotate. This creates a pressure difference across the oil guiding device 51 as a part of the oil transport device 50 (see FIG. 4B).

[0084] With reference to FIG. 4B the oil is taken from the front side of the oil transport device 50 and is flowing through the oil guiding device 51 (see oil flow O through an oil channel 58 in FIG. 4B) towards the pump wheels 53 and then through oil holes 54 towards the target location 60. The target location here is the planet carrier 36 of the gearbox 30. The oil coming from the auxiliary oil distribution system is rotating with the gearbox planet carrier 36, so that it and other parts of the gearbox 30 can be lubricated without any other part for transferring oil between the two components at different speeds.

[0085] The oil flow O is guided by a scoop device 52 (see FIG. 4B) which is circumferentially positioned at the entrance of the oil channel 58 of the oil guiding device 51. With this scoop device 52 oil being accelerated radially outwards due to a centrifugal force is captured and guided into the channel 58 of the oil guiding device 51.

[0086] In FIGS. 6A, 6B a second embodiment is shown which has essentially the same functionality as the first embodiment so reference can be made to the respective description above.

[0087] In the second embodiment, the oil transport device 50 comprises an inner ring 55 with the toothed rack driving the pump wheels. The inner ring 55 is connected to a static part of the gear box 30 and the outer ring 56 of the oil transport device 50 is connected to the planet carrier 38, i.e. the pump wheels are driven through a rotation of the outer ring 56 rather than the inner ring 55 in the first embodiment.

[0088] The oil flow through the oil channel 58 and pumping of the oil by the pump wheels 53 is analogue to the first embodiment.

[0089] In FIGS. 7A, 7B, 8A and 8B a third embodiment is shown which has essentially the same functionality as the first embodiment so reference can be made to the respective description above.

[0090] In this embodiment a ring gear 59 with a toothed rack at the insides of the outer circumference of the oil transport device 50 is connected to a static part. The housing of the oil transport device 50 operates as carrier plate 61 connected to a rotating part of the gearbox 30, i.e. the planet carrier 34. Therefore, the carrier plate 61 rotates and drives the pump wheels 53 which then transport the pol as in the other embodiments

[0091] It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

LIST OF REFERENCE NUMBERS

[0092] 9 principal rotational axis [0093] 10 gas turbine engine [0094] 11 engine core [0095] 12 air intake [0096] 14 low-pressure compressor [0097] 15 high-pressure compressor [0098] 16 combustion equipment [0099] 17 high-pressure turbine [0100] 18 bypass exhaust nozzle [0101] 19 low-pressure turbine [0102] 20 core exhaust nozzle [0103] 21 nacelle [0104] 22 bypass duct [0105] 23 propulsive fan [0106] 24 stationary support structure [0107] 26 shaft [0108] 27 interconnecting shaft [0109] 28 sun gear [0110] 30 gearbox [0111] 32 planet gears [0112] 34 planet carrier [0113] 36 linkages [0114] 38 ring gear [0115] 40 linkages [0116] 41 housing of gearbox [0117] 50 oil transport device [0118] 51 oil guiding device [0119] 52 scoop device [0120] 53 pump wheels in oil transport device [0121] 54 oil exit hole [0122] 55 inner ring of oil transport device [0123] 56 outer ring of oil transport device [0124] 57 cavity for pump wheel [0125] 58 oil channel [0126] 59 ring gear of oil transport device [0127] 60 oil target location [0128] 61 carrier plate of oil transport device [0129] A core airflow [0130] B bypass airflow [0131] O oil flow