SEALING SYSTEM, GEAR BOX WITH SEALING SYSTEM AND A GAS TURBINE ENGINE WITH SEALING SYSTEM

Abstract

The invention relates to a planetary gear box having at least one seal system, which has at least one rectangular-section sealing ring, which is arranged in a groove device, wherein the at least one rectangular-section sealing ring rests at least partially against a groove flank of the groove device, and the groove flank has profiling between the groove flank and the rectangular-section sealing ring for the purpose of distributing fluid, in particular oil, applied to the seal system, wherein the at least one seal system is part of an oil supply of a planet carrier and the seal system has at least two rectangular-section sealing rings, which are spaced apart axially from one another and are arranged radially between a drive shaft of the planetary gear box and the planet carrier. The invention also relates to a gas turbine engine.

Claims

1. A planetary gear box having at least one seal system, which has at least one rectangular-section sealing ring, which is arranged in a groove device, wherein the at least one rectangular-section sealing ring rests at least partially against a groove flank of the groove device, and the groove flank has profiling between the groove flank and the rectangular-section sealing ring for the purpose of distributing fluid, in particular oil, applied to the seal system, wherein the at least one seal system is part of an oil supply of a planet carrier and the seal system has at least two rectangular-section sealing rings, which are spaced apart axially from one another and are arranged radially between a drive shaft of the planetary gear box and the planet carrier.

2. The planetary gear box according to claim 1, wherein the profiling is designed as a lubricating pocket.

3. The planetary gear box according to claim 1, wherein the groove device is arranged in a static part or a rotationally moved part.

4. The planetary gear box according to claim 1, wherein a hydrodynamic or hydrostatic design of an equilibrium of forces across the rectangular-section sealing ring, in particular by a hydrodynamic or hydrostatic design of the lubricating pocket.

5. The planetary gear box according to claim 1, wherein the material of the groove flank is of relatively harder design than the rectangular-section sealing ring.

6. The planetary gear box according to claim 1, wherein the groove device has a groove with a rectangular cross section having a width between 1.5 and 10 mm, in particular between 5 and 10 mm, and a depth between 1 and 10 mm, in particular between 5 and 10 mm.

7. The planetary gear box according to claim 1, wherein the groove device has a diameter between 50 and 500 mm, in particular between 300 and 500 mm, at the radial base.

8. The planetary gear box according to claim 1, wherein the groove device is composed of two parts, wherein the groove flank is, in particular, part of a disc or of a flange ring.

9. The planetary gear box according to claim 1, wherein it is arranged in a gear box or at a shaft feed-through.

10. The planetary gear box according to claim 1, wherein the at least one rectangular-section sealing ring is produced from plastic, in particular a polyimide or polyether ether ketone and/or metal, or comprises these materials.

11. The planetary gear box according to claim 1, wherein said gear box is arranged in a wind turbine or a motor vehicle.

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. A gas turbine engine for an aircraft, said gas turbine engine comprising the following: a core engine comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan, which is positioned upstream of the core engine, wherein the fan comprises a plurality of fan blades; and a planetary gear box, according to claim 1, which can be driven by the core shaft, wherein the fan can be driven by means of the planetary gear box at a lower speed than the core shaft.

Description

[0051] Embodiments will now be described by way of example, with reference to the figures, in which:

[0052] FIG. 1 shows a sectional side view of a gas turbine engine having one embodiment of a planetary gear box;

[0053] FIG. 2 shows a close-up sectional side view of an upstream portion of a gas turbine engine;

[0054] FIG. 3 shows a partially cut-away view of a gear box for a gas turbine engine;

[0055] FIG. 4 shows a sectional view through a seal system which can be used in one embodiment of a planet gear;

[0056] FIG. 5 shows a perspective view of a groove flank of an embodiment of a seal system;

[0057] FIG. 5A shows a perspective view of a groove flank an alternative embodiment of a seal system;

[0058] FIG. 5B shows a perspective view of a groove flank an alternative embodiment of a seal system;

[0059] FIG. 6 shows a sectional view through part of one embodiment of a planetary gear box having a seal system.

[0060] Before embodiments and details of a planetary gear box 30 having a seal system 100 are described (see FIG. 6), an area of application, namely a gas turbine engine 10 of an aircraft, will be described in conjunction with FIGS. 1 to 3. In FIGS. 4 and 5, details of profiling for oil distribution in the seal system 100 are then described, it being possible to use said details in embodiments of the planetary gear box 30.

[0061] FIG. 1 illustrates a gas turbine engine 10 having a main axis of rotation 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 the low-pressure turbines 17, 19 and thereby drive said turbines, before being expelled through the nozzle 20 to provide a certain propulsive thrust. The high-pressure turbine 17 drives the high-pressure compressor 15 by means of a suitable connecting shaft 27. The fan 23 generally provides the major part of the propulsive thrust. 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. 2. The low-pressure turbine 19 (see FIG. 1) 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. Radially to the outside of the planet gears 32 and meshing therewith is an annulus or ring gear 38 that is coupled, via linkages 40, to a stationary support structure 24.

[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 can be referred to as a first, or lowest-pressure, compression stage.

[0065] The epicyclic planetary gear box 30 is shown by way of example in greater detail in FIG. 3. The sun gear 28, planet gears 32 and ring gear 38 in each case comprise teeth on their periphery to allow intermeshing with the other gearwheels. However, for clarity, only exemplary portions of the teeth are illustrated in FIG. 3. Although four planet gears 32 are illustrated, it will be apparent to the 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. 2 and 3 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 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 can be a differential gear box in which both the ring gear 38 and the planet carrier 34 are allowed to rotate.

[0067] 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 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. By way of a further example, the connections (such as the linkages 36, 40 in the example of FIG. 2) 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. 2. 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 supporting linkages and bearing positions would usually be different from that shown by way of example in FIG. 2.

[0068] Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gear box types (for example star or epicyclic-planetary), supporting 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. 1 has a split flow nozzle 20, 22, which means that the flow through the bypass duct 22 has a dedicated nozzle, which is separate from the engine core nozzle 20 and is radially on the outside with respect to the latter. 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 area. Whilst the described example relates to a turbofan engine, the disclosure may be applied, for example, to any type of gas turbine engine, such as an open-rotor (in which the fan stage is not surrounded by an engine nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine 10 may 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, comprising an axial direction (which is aligned with the axis of rotation 9), a radial direction (in the bottom-to-top direction in FIG. 1), and a circumferential direction (perpendicular to the view in FIG. 1). The axial, radial and circumferential directions run so as to be mutually perpendicular.

[0072] At various points in the planetary gear box 30, it may be necessary to provide seal systems 100, as will be shown in conjunction with FIG. 6.

[0073] First of all, however, details of one configuration of a seal system 100 will be given. FIG. 4 illustrates a sectional view through part of a seal system 100, the intention here being to provide sealing between a static part 55 and a rotating part 56 against a relatively high oil pressure p on the right-hand side.

[0074] For this purpose, a rectangular-section sealing ring 50 is arranged in a groove device 51 of the static part 55. Here, the groove device 51 is formed substantially in a U shape in the static part 55, wherein the rectangular-section sealing ring 50 does not completely fill the groove device 51. In this arrangement, one side of the rectangular-section sealing ring 50 is subject to the oil pressure p which fills the groove device 51.

[0075] One side—here the right-hand side—of the rectangular-section sealing ring 50 is subject to the oil pressure p, which is relatively high in comparison with the left-hand side and which pushes the rectangular-section sealing ring 50 to the left against a groove flank 52. Between the base of the groove device 51 and the inside of the rectangular-section sealing ring 50, the oil pressure p can exert a radially outward pressing action on the rectangular-section sealing ring 50. The outside of the rectangular-section sealing ring 50 is thereby pressed in a sealing manner against the inside of the rotating part 56.

[0076] In the case of the profiling, it is possible to distinguish fundamentally between two general physical principles. In the case of hydrostatically acting structures, a counter pressure is built up in the region of the contact surface by the applied fluid, reducing the load on the sealing ring and thus reducing wear, for example, since the ring is subject to less severe loads. In the case of hydrodynamically acting structures, a fluid film forms between the ring and the groove, significantly reducing wear.

[0077] Arranged in the groove flank 52 is profiling 53 for the purpose of distributing oil, and this profiling will be described in greater detail below. Here, the profiling 53 is designed as a lubricating pocket, for example, as illustrated schematically in FIG. 5. By virtue of the profiling 53, the oil pressure p can also take effect from the side of the groove flank 52, leading to an improved equilibrium of pressure across the rectangular-section sealing ring 50. By reducing the loads, a reduction in wear or abrasion is achieved.

[0078] Thus, it is not necessary to arrange such lubricating pockets in the rectangular-section sealing ring 50 itself, which would be expensive and these pockets could also be damaged by abrasion, for example.

[0079] If the sealing device 100 is produced integrally from a single component, the profiling 53 can be introduced into the groove flank 52 by a laser method, for example.

[0080] Another possibility for the construction is also illustrated in FIG. 4. The static part 55 can be composed of two parts, for example. In this case, a first part (here on the left) of the groove device 51a can be designed as a disc, for example, with the result that the groove flank 52 (and the profiling 53) would occupy an annular region on the disc. A disc 51a of this kind could easily be machined in order to introduce profiling 53.

[0081] A second part (here on the right) of the groove device 51b can then be designed as a shaft part with an offset. When the parts 51a, 51b are assembled, the substantially U-shaped construction of the groove device 51 is obtained.

[0082] For typical applications, such as those which are illustrated in conjunction with FIG. 6, the groove device 51 has a groove of rectangular cross section with a width between 5 and 10 mm and a depth between 5 and 10 mm. The groove device 51 can likewise have a diameter between 300 and 500 mm at the radial base.

[0083] In this case, the rectangular-section sealing ring 50 can be produced from plastic, for example, in particular a polyimide or a polyether ether ketone and/or metal (e.g. cast materials), or can comprise these materials. In this case, the material of the groove flank 52 will generally be harder than the material of the rectangular-section sealing ring 51.

[0084] By means of such a configuration, relative speeds at the sealing surface of 20 to 60 m/s can be achieved and pressure differences of 10 to 30 bar can be sealed off.

[0085] FIG. 6 illustrates an application of a seal system 100 in a planetary gear box 30 of the kind that can be used in a gas turbine engine 10 (see FIGS. 1 to 3), for example.

[0086] In this case, the sun gear 28 and a journal 61 of a planet gear 32 are illustrated here. The planet gear 32 can rotate around the journal 61, wherein this mounting of the planet gear 32 must be lubricated.

[0087] Here, the sun gear 28 of the planetary gear box 30 is driven via a drive shaft 60. An oil supply is illustrated radially outside the drive shaft 60, wherein oil is fed in under pressure from the right through the channels indicated in black from the region of the casing of the gas turbine engine 10.

[0088] The seal system 100 used here has two axially mutually spaced rectangular-section sealing rings 50 in the static part 55 in the oil feed. Here, sealing is performed with respect to the rotating part 56 of the planet carrier 34. The groove devices 51 in which the rectangular-section sealing rings 50 are arranged have groove flanks 52 with profiling 53 corresponding to the embodiment shown in FIG. 4. However, it is also possible in principle for the seal system 100 to provide sealing between a drive shaft of the planetary gear box 30 and the planet carrier 34. It is also possible for more than two axially mutually spaced rectangular-section sealing rings 50 to be used.

[0089] This shows that the seal system 100 can also have more than one rectangular-section sealing ring 50.

[0090] Seal systems of the type described here can also be used for other sealing tasks, e.g. in internal combustion engines or wind turbines. Moreover, the seal systems 100 have here been described in conjunction with oil, which is used as a lubricant. In principle, it is also possible to use seal systems 100 of this kind for sealing with respect to other fluids.

[0091] It will be understood 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 which are described here.

LIST OF REFERENCE SIGNS

[0092] 9 Main axis of rotation [0093] 10 Gas turbine engine [0094] 11 Core engine [0095] 12 Air inlet [0096] 14 Low-pressure compressor [0097] 15 High-pressure compressor [0098] 16 Combustion device [0099] 17 High-pressure turbine [0100] 18 Bypass thrust nozzle [0101] 19 Low-pressure turbine [0102] 20 Core thrust nozzle [0103] 21 Engine nacelle [0104] 22 Bypass channel [0105] 23 Fan [0106] 24 Stationary supporting structure [0107] 26 Shaft [0108] 27 Connecting shaft [0109] 28 Sun gear [0110] 30 Gear box, planetary gear box [0111] 32 Planet gears [0112] 34 Planet carrier [0113] 36 Linkage [0114] 38 Ring gear [0115] 40 Linkage [0116] 50 Rectangular-section sealing ring [0117] 51 Groove device [0118] 51a First part of the groove device [0119] 51b Second part of the groove device [0120] 52 Groove flank [0121] 53 Profiling in groove flank [0122] 55 Static part of the seal system [0123] 56 Rotating part of the seal system [0124] 60 Drive shaft [0125] 61 Journal for planet gear [0126] 100 Seal system [0127] A Core air flow [0128] B Bypass air flow [0129] p Oil pressure