GEAR UNIT ASSEMBLY FOR AN ENGINE WITH LEAKAGE RECOVERY

Abstract

A gear box assembly for an engine, having a gear box for transmitting a torque, at least one first, static part, at least one second, rotating part, which is mounted so as to be rotatable relative to the first, static part and on which at least one element of the gear box is provided, and a conduit system for conveying a fluid to elements of the gear box,
wherein the conduit system has at least one first supply line and one second supply line for supplying fluid to at least one element of the gear box.

A leakage recovery facility is provided, by means of which at least a proportion of a leakage flow of fluid which originates from a first duct portion of the first supply line and which flows across at least one seal can be conducted to the second supply line.

Claims

1. A gear box assembly for an engine, having a gear box for transmitting a torque, at least one first, static part, at least one second, rotating part, which is mounted so as to be rotatable relative to the first, static part and on which at least one element of the gear box is provided, and a conduit system for conveying a fluid to elements of the gear box, wherein the conduit system has at least one first supply line and one second supply line for supplying fluid to at least one element of the gear box, and wherein the first supply line has a first duct portion in the first, static part and a second duct portion in the second, rotating part, and the second duct portion is connected to the first duct portion via a transition region that is sealed off with respect to the second, rotating part by means of at least one seal, wherein a leakage recovery facility is provided, by means of which at least a proportion of a leakage flow of fluid which originates from the first duct portion and which flows across the at least one seal can be conducted to the second supply line.

2. The gear box assembly according to claim 1, wherein the leakage recovery facility comprises a feed opening which is situated, in relation to the leakage flow, downstream of the at least one seal in the second, rotating part and via which inflowing fluid can be conducted to a connecting conduit that is connected to the second supply line.

3. The gear box assembly according to claim 2, wherein the leakage recovery facility is configured to, during the operation of the gear box, convey fluid of the leakage flow through the feed opening in the direction of the connecting conduit under the action of a centrifugal force.

4. The gear box assembly according to claim 2, wherein the leakage recovery facility comprises, downstream of the feed opening, at least one catch plate that projects radially in relation to a rotation axis of the second, rotating part.

5. The gear box assembly according to claim 1, wherein the conduit system has at least two seals which are spaced apart from one another axially in relation to a rotation axis of the second, rotating part, and, by means of the leakage recovery facility, both at least a proportion of a leakage flow of fluid which originates from the first duct portion and which flows across a first seal and at least a proportion of a leakage flow of fluid which originates from the first duct portion and which flows across an axially spaced-apart second seal can be conducted to the second supply line.

6. The gear box assembly according to claim 2, wherein the leakage recovery facility comprises at least two feed openings in the second, rotating part, via each of which inflowing fluid can be conducted to a connecting conduit connected to the second supply line and between which, in an axial direction in relation to a rotation axis of the second, rotating part, the first and second seals are provided.

7. The gear box assembly according to claim 6, wherein the leakage recovery facility comprises at least two catch plates which each project radially and which are assigned to a respective feed opening.

8. The gear box assembly according to claim 1, wherein the leakage recovery facility comprises, on the first, static part, at least one catch pan for fluid from a leakage flow.

9. The gear box assembly according to claim 1, wherein the first and second supply lines are provided for the redundant supply of fluid to at least one element of the gear box.

10. The gear box assembly according to claim 1, wherein the first and/or second supply line are/is provided for conveying the fluid to at least one bearing, which is to be lubricated with the fluid, of the gear box.

11. The gear box assembly according to claim 1, wherein the gear box is configured as a planetary gear box.

12. The gear box assembly according to claim 11, wherein the conduit system is part of an oil supply for a planet carrier of the planetary gear box.

13. The gear box assembly according to claim 12, wherein the conduit system is provided for lubricating a bearing arrangement by means of which a planet gear of the planetary gear box is mounted rotatably on the planet carrier.

14. The gear box assembly according to claim 11, wherein the first and second duct portions are arranged radially offset with respect to one another in relation to a rotation axis of the gear box.

15. An engine having a gear box assembly according to claim 1.

16. The engine according to claim 15, which at least comprises: a core engine that comprises a turbine, a compressor, and a core shaft connecting the turbine to the compressor, and a fan that is positioned upstream of the core engine, wherein the fan comprises a plurality of fan blades, wherein the gear box of the gear box assembly can be driven by the core shaft, and the fan can be driven at a lower rotational speed than the core shaft by means of the gear box.

Description

[0053] The appended figures illustrate, by way of example, possible design variants of the proposed solution.

[0054] In the figures:

[0055] FIG. 1 shows a detail of a design variant of a proposed gear box assembly;

[0056] FIG. 2 schematically shows a further design variant in which a first, static part of the gear box assembly is arranged radially at the outside and a second, rotating part is arranged radially at the inside;

[0057] FIG. 3 shows a lateral sectional view of a gas turbine engine in which a proposed gear box assembly is used;

[0058] FIG. 4 shows a close-up lateral sectional view of an upstream portion of a gas turbine engine of FIG. 3;

[0059] FIG. 5 shows a partially cut-away view of a gear box for a gas turbine engine of FIGS. 3 and 4.

[0060] Before design variants of a proposed gear box assembly having a conduit system 5 are described in more detail, a field of application of the proposed solution, namely a gas turbine engine 10 of an aircraft, will be described in conjunction with FIGS. 3 to 5.

[0061] FIG. 3 illustrates a gas turbine engine 10 having a main rotation axis 9. The engine 10 comprises an air intake 12 and a fan 23 that generates two air flows: a core air flow A and a bypass air flow B. The gas turbine engine 10 comprises a core 11 that receives the core air flow A. When viewed in the order corresponding to the axial direction of flow, the core engine 11 comprises a low-pressure compressor 14, a high-pressure compressor 15, a combustion device 16, a high-pressure turbine 17, a low-pressure turbine 19, and a core thrust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass thrust nozzle 18. The bypass air flow 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 planetary gear box 30.

[0062] During operation, the core air flow 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 expelled from the high-pressure compressor 15 is directed into the combustion device 16, where it is mixed with fuel and the mixture is combusted. The resulting hot combustion products then propagate through the high-pressure and low-pressure turbines 17, 19 and thereby drive said turbines, before being expelled through the nozzle 20 to provide a certain thrust force. The high-pressure turbine 17 drives the high-pressure compressor 15 by way of a suitable connecting shaft 27. The fan 23 generally provides the major part of the thrust force. The epicyclic planetary gear box 30 is a reduction gear box.

[0063] An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. 3. The low-pressure turbine 19 (see FIG. 3) drives the shaft 26, which is coupled to a sun gear 28 of the epicyclic planetary gear box 30. Multiple planet gears 32, which are coupled to one another by a planet carrier 34, are situated radially to the outside of the sun gear 28 and mesh therewith. The planet carrier 34 guides the planet gears 32 in such a way that they circulate synchronously around the sun gear 28, 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. An external gear or ring gear 38 that is coupled via linkages 40 to a stationary support structure 24 is situated radially to the outside of the planet gears 32 and meshes therewith.

[0064] It should be noted that the expressions “low-pressure turbine” and “low-pressure compressor”, as used herein, can be taken to mean the lowest-pressure turbine stage and lowest-pressure compressor stage (i.e. not including the fan 23), respectively, and/or the turbine and compressor stages that are connected together by the connecting shaft 26 with the lowest rotational speed in the engine (i.e. not including the gear box output shaft that drives the fan 23). In some documents, the “low-pressure turbine” and the “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.

[0065] The epicyclic planetary gear box 30 is shown in greater detail by way of example in FIG. 5. The sun gear 28, planet gears 32 and ring gear 38 in each case comprise teeth on their periphery to allow meshing with the other toothed gears. However, for clarity, only exemplary portions of the teeth are illustrated in FIG. 5. Although four planet gears 32 are illustrated, it will be apparent to a person skilled in the art that more or fewer planet gears 32 may be provided within the scope of protection of the claimed invention. Practical applications of an epicyclic planetary gear box 30 generally comprise at least three planet gears 32.

[0066] The epicyclic planetary gear box 30 illustrated by way of example in FIGS. 4 and 5 is a planetary gear box in which the planet carrier 34 is coupled to an output shaft via linkages 36, with the ring gear 38 being fixed. However, any other suitable type of planetary gear box 30 may be used. As a further example, the planetary gear box 30 may be a star arrangement, in which the planet carrier 34 is held fixed, with the ring gear (or external gear) 38 being allowed to rotate. In such an arrangement, the fan 23 is driven by the ring gear 38. As a further alternative example, the gear box 30 may be a differential gear box in which both the ring gear 38 and the planet carrier 34 are allowed to rotate.

[0067] It is self-evident that the arrangement shown in FIGS. 4 and 5 is merely an example, and various alternatives fall within the scope of protection of the present disclosure. Purely by way of example, any suitable arrangement can be used for positioning the gear box 30 in the engine 10 and/or for connecting the gear box 30 to the engine 10. Byway of a further example, the connections (such as the linkages 36, 40 in the example of FIG. 4) between the gear box 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft and the fixed structure 24) may have a certain degree of stiffness or flexibility. As a further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine 10 (for example between the input and output shafts of the gear box and the fixed structures, such as the gear casing) may be used, and the disclosure is not limited to the exemplary arrangement of FIG. 4. For example, where the gear box 30 has a star arrangement (described above), a person skilled in the art would readily understand that the arrangement of output and support linkages and bearing positions would usually be different from that shown byway of example in FIG. 4.

[0068] Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gear box types (for example star-shaped or epicyclic-planetary), support structures, input and output shaft arrangement, and bearing positions.

[0069] Optionally, the gear box may drive additional and/or alternative components (for example the intermediate-pressure compressor and/or a booster compressor).

[0070] Other gas turbine engines in which the present disclosure can be used may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As a further example, the gas turbine engine shown in FIG. 3 has a split flow nozzle 20, 22, meaning that the flow through the bypass duct 22 has its own nozzle, which is separate from and radially outside the engine core nozzle 20. However, this is not restrictive, and any aspect of the present disclosure can 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) can have a fixed or variable region. Although the example described relates to a turbofan engine, the disclosure may be applied for example to any type of gas turbine engine, for example an open-rotor engine (in which the fan stage is not surrounded by an engine nacelle) or a turboprop engine. In some arrangements, the gas turbine engine 10 potentially does not comprise a gear box 30.

[0071] The geometry of the gas turbine engine 10, and components thereof, is/are defined by a conventional axis system, which comprises an axial direction (which is aligned with the rotation axis 9), a radial direction (in the direction from bottom to top in FIG. 3), and a circumferential direction (perpendicular to the view in FIG. 3). The axial, radial and circumferential directions are mutually perpendicular.

[0072] For lubrication and/or heat dissipation, provision may be made for a friction-releasing and/or cooling fluid, for example oil, to be conveyed to various points of the planetary gear box 30. For example, specifically with regard to the high rotational speeds of rotating (gear box) elements of the planetary gear box 30, provision may be made for oil to be supplied to bearings for these rotating elements and/or to toothed gear pairings at this planetary gear box 30. This relates for example to a plain bearing arrangement for a planet gear 32 on the planet carrier 34. Here, in order to provide the greatest possible degree of fail safety, a conduit system 5 is provided for conveying oil to a corresponding plain bearing, which conduit system comprises two supply lines 5A and 5B, via which oil can be conducted in redundant fashion to the respective planet gear 32. A supply line 5A, 5B may then for example also be coupled to a respectively dedicated oil pump.

[0073] In the present case, the planet gear 32 rotates in each case about a journal 61 of the planetary gear box 30. This journal 61 is likewise illustrated as a detail in FIG. 1 together with a sun gear 28 of the planetary gear box 30. The sun gear 28 of the planetary gear box 30 can be driven via a drive shaft 60. In relation to a rotation axis of the sun gear 28 or of the drive shaft 60, the conduit system with the first supply line 5A is situated radially further to the outside, in order to convey oil under pressure through channels of the conduit system 5 from the region of the casing of the gas turbine engine 10 in the direction of the planetary gear box 30 (from the right in FIG. 1).

[0074] During the conveyance of oil to the planet carrier 32, there is however then the fundamental difficulty that the oil must be conveyed from a first, static part 55 in the gas turbine engine 10 to a second, rotating part 56, which is connected to the planet carrier 32. For this purpose, in the design variant illustrated in FIG. 1, a first, static duct portion 550 of the first, static part 55 and a second, rotating duct portion 560 of the rotating part 56 are connected to one another via a transition region 54 such that oil can flow from the static duct portion 550 of the rotating part 55 into the rotating duct portion 560 of the rotating part 561 in order to convey oil via the first supply line 5A to the plain bearing of the planet carrier 32. One or more outflow openings of the first duct portion 550 into the transition region 54 are thus in this case situated opposite one or more inflow openings of the second duct portion 560 at the transition region 54, such that oil can flow across the transition region 54 from the first duct portion 550 into the second duct portion 560.

[0075] In order to be able to convey oil via the first supply line 5A in the direction of the planet carrier 32, a seal is provided between the static part 55 and the rotating part 56 at the transition region 54. The transition region 54 is thus sealed off with respect to the second rotating part 56, wherein, for this purpose, seals 50a and 50b, in this case each in the form of circumferentially encircling sealing rings (for example in the form of rectangular-section sealing rings) are provided to both sides of the transition region 54 in an axial direction. The seals 50a and 50b are arranged in associated groove devices of the static part 55. A groove device is in this case formed, so as to be substantially U-shaped in cross section, in the static part 55, wherein the respective seal 50a, 50b does not completely fill its groove device. During the operation of the gas turbine engine 10 and thus during the operation of the planetary gear box 30, it is thus in particular not possible to entirely rule out a situation in which an at least slight leakage flow passes across the respective seal 50a or 50b. Here, a corresponding leakage flow reduces the oil quantity that is available for the first supply line 5A.

[0076] As part of the illustrated design variant of the proposed solution, provision is now made for the conduit system 5 to be equipped with a leakage recovery facility 57, by means of which in each case at least a proportion of a leakage flow of oil which originates from the first duct portion 550 and which flows across one of the seals 50a and 50b is conducted to the second supply line 5B. Oil which escapes from the transition region 54 and which is attributable to a leak in the region of one of the seals 50a, 50b is in this case consequently utilized for the second supply line 5B that is provided for the redundant lubrication of the bearing arrangement of a planet gear 34.

[0077] For this purpose, the leakage recovery facility 57 has two feed openings 571 and 572 in the second, rotating part 56. Each feed opening 571, 572, which may then for example also be of circumferentially encircling form on a radially inner side of the second, rotating part 56, is assigned to one of the seals 50a, 50b. Thus, in relation to a possible leakage flow across a first seal 50a, a first feed opening 571 is situated downstream of, and thus so as to be spaced apart in a first axial direction along the rotation axis of the second, rotating part 56 from, the first seal 50a (and thus to the left of the first seal 50a in the cross-sectional view of FIG. 1). In turn, in relation to a possible leakage flow across said second seal 50b, the other, second feed opening 572 is situated downstream of, and so as to be spaced apart axially in an opposite axial direction from, the second seal 50b (and thus to the right of the second seal 50b in the cross-sectional view of FIG. 1). The transition region 54, with the seals 50a and 50b that border it axially, is thus consequently situated between the two feed openings 571 and 572. In the event of any leak in the region of the seals 50a, 50b, it is thus possible for oil that originates from a leak to be conveyed, under the action of the centrifugal force that arises during the operation of the planetary gear box 30, via a respective feed opening 571 or 572 into a connecting conduit 573 that opens into the second supply line 5b. Here, the feed openings 571 and 572 are each part of at least partially radially extending conduit portions within the second, rotating part 56, which each open into the connecting conduit 573.

[0078] In the design variant illustrated, downstream of at least one or else of both feed openings 571, 572, there is provided in each case one radially projecting catch plate 574a or 574b of the leakage recovery facility 57. The respective, annularly encircling catch plate 574a, 574b projects in each case radially inwards on the second, rotating part 56 and thus delimits a space that is available in an axial direction for a respective leakage flow that occurs across a respective seal 50a or 50b. One or more catch plates 574a, 574b may be advantageous in particular with regard to relatively high outflow speeds of a leakage flow.

[0079] FIG. 2 schematically illustrates a further design variant of the proposed solution. Here, by contrast to the design variant of FIG. 1, the second, rotating part 56 is arranged radially at the inside. The first, static part 55 is thus situated radially at the outside.

[0080] Analogously to the design variant of FIG. 1, a leakage recovery facility 57 is also provided here in order to conduct at least a proportion of a leakage flow of fluid, which originates from the duct portion 550 and which flows across one of the seals 50a, 50b, to the second supply line 5B of the second, rotating part 56. Owing to the “reversed” arrangement of the static and rotating parts 55, 56 in relation to the design variant of FIG. 1, the leakage recovery facility 57 additionally comprises a static (first) catch pan 575. Oil that has escaped from the transfer region 54 as leakage across the seals 50a, 50b is collected at this catch pan 575, which is situated radially further to the outside than the first, static part 55.

[0081] Oil can be conducted radially further outwards from the first, static catch pan 575 via one or more connecting openings 5750 at the static catch pan 575. In the present case, oil originating from a leak is conducted in this way to a second (rotating) catch or collecting pan 565 on the second, rotating part 56. Oil is fed from this second catch or collecting pan 565 to the second supply line 5B.

[0082] In the illustrated design variant of a proposed gear box assembly corresponding to FIG. 1 or 2, oil that is attributable to a leak in the first supply line 5A in the transition region 54 thus passes in each case at least partially or entirely into the second supply line 5B, which is likewise provided for lubrication of the bearing arrangement of the planet gears 34. In this way, a gear box assembly with the planetary gear box 30 and the conduit system 5 can be made more lightweight, because, during operation, any leakage in the transition region 54 of the first supply line 5A does not inevitably lead to a significant loss of oil in the system as a whole, and therefore a quantity of oil that must be provided in the conduit system 5 is lower. Furthermore, a certain leakage in the region of the seals 50a, 50b can be more easily tolerated with regard to improved wear characteristics of the seals 50a, 50b. This in turn improves the robustness of the planetary gear box 30 with respect to any wear-induced damage to the seals 50a, 50b.

[0083] It is self-evident that the invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the concepts described herein. Any of the features may be used separately or in combination with any other features, unless they are mutually exclusive, and the disclosure extends to and includes all combinations and subcombinations of one or more features that are described herein.

LIST OF REFERENCE DESIGNATIONS

[0084] 9 Main rotation axis [0085] 10 Gas turbine engine [0086] 11 Core engine [0087] 12 Air inlet [0088] 14 Low-pressure compressor [0089] 15 High-pressure compressor [0090] 16 Combustion device [0091] 17 High-pressure turbine [0092] 18 Bypass thrust nozzle [0093] 19 Low-pressure turbine [0094] 20 Core thrust nozzle [0095] 21 Engine nacelle [0096] 22 Bypass duct [0097] 23 Fan [0098] 24 Stationary support structure [0099] 26 Shaft [0100] 27 Connecting shaft [0101] 28 Sun gear [0102] 30 (Planetary) gear box [0103] 32 Planet gears [0104] 34 Planet carrier [0105] 36 Linkage [0106] 38 Ring gear [0107] 40 Linkage [0108] 5 Conduit system [0109] 5A, 5B First/second supply line [0110] 50a, 50b Seal [0111] 54 Transition region [0112] 55 Static part [0113] 550 Static duct portion [0114] 56 Rotating part [0115] 560 Rotating duct portion [0116] 565 Catch/collecting pan [0117] 57 Leakage recovery facility [0118] 571, 572 Feed opening [0119] 573 Connecting conduit [0120] 574a/b Catch plate [0121] 575 Catch pan [0122] 5750 Connecting opening [0123] 60 Drive shaft [0124] 61 Journal for planet gear [0125] A Core air flow [0126] B Bypass air flow