GEAR BOX CASING AND METHOD FOR PRODUCING A GEAR BOX CASING

Abstract

A gear-box casing in a gas turbine engine, in particular an aircraft engine, characterized in that the gear-box casing has partially a region including fiber reinforced plastic, the fibers in this region being arranged only in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation of the gear-box casing. The invention also concerns a method for producing a gear-box casing and a gas turbine engine.

Claims

1. A gear-box casing in a gas turbine engine, in particular an aircraft engine, wherein the gear-box casing has partially a region comprising fiber reinforced plastic, the fibers in this region being arranged only in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation of the gear-box casing, and between the input side and the output side there is arranged at least one conical region, wherein at the axial center of the at least one conical region the fibers are arranged in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation, the angle becoming greater in the direction of a larger diameter and the angle becoming smaller in the direction of a smaller diameter.

2. A gear-box casing according to claim 1, wherein a metal insert is arranged at a load introduction point and/or at a load delivery point of the gear-box casing.

3. A gear-box casing according to claim 1, wherein the fibers are at least partially formed as monolayers.

4. (canceled)

5. (canceled)

6. A gear-box casing according to claim 5, wherein the fiber volume content is at a maximum in the at least one conical region, even independently of the angle of the fiber deposition.

7. A gear-box casing according to claim 1, wherein additional layers of fibers, in particular in a load-adapted orientation, are arranged in the region of the input side and/or the region of the output side.

8. A gear-box casing according to claim 1, wherein the fiber-reinforced plastic comprises carbon fibers, metal filaments, synthetic fibers, in particular aramids and/or ceramic fibers.

9. A method for producing a gear-box casing for the input side of a gear box in a gas turbine engine, in particular an aircraft engine, wherein in one region fibers are incorporated in a matrix, the fibers in this region being arranged only in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation of the gear-box casing, and at the axial center of a conical region, the fibers are arranged in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation, the winding angle becoming greater in the direction of a larger diameter and the winding angle becoming smaller in the direction of a smaller diameter.

10. The method according to claim 9, wherein depositing the fibers is performed without crossing points and/or with minimal fiber undulation.

11. The method according to claim 9, wherein a winding method, a braiding method, a TFP method or a combination of the methods is used for introducing the fibers.

12. (canceled)

13. The method according to claim 12, wherein the fiber volume content is kept at a maximum in the conical region, even independently of the angle of the fiber deposition.

14. The method according to claim 9, wherein the fiber-reinforced plastic comprises carbon fibers, metal filaments, synthetic fibers, in particular aramids and/or ceramic fibers.

15. A gas turbine engine for an aircraft, 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 gear box, which can be driven by the core shaft, wherein the fan can be driven by means of the gear box at a lower rotational speed than the core shaft, wherein a gear-box casing according to claim 1 is connected to the gear box.

16. Gear-box casing according to claim 1, wherein the at least one conical region tapers in the axial direction.

Description

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

[0050] FIG. 1 shows a sectional lateral view of a gas turbine engine;

[0051] FIG. 2 shows a close-up sectional lateral view of an upstream portion of a gas turbine engine;

[0052] FIG. 3 shows a partially cut-away view of a gear box for a gas turbine engine;

[0053] FIG. 4 shows an exploded partial view of a first embodiment of a gear-box casing;

[0054] FIG. 5 shows a side partial view of an embodiment of a gear-box casing according to FIG. 4;

[0055] FIG. 6 shows a perspective view of the embodiment according to FIG. 4;

[0056] FIG. 7 shows a perspective view of a further embodiment of a gear-box casing having conical regions;

[0057] FIG. 8 shows a side view of the embodiment according to FIG. 7;

[0058] FIG. 9 shows a representation of the normalized flexural rigidity and the normalized torsional rigidity in dependence on the fiber angle.

[0059] FIG. 1 illustrates a gas turbine engine 10 having a main axis of rotation 9. The gas turbine engine 10 comprises an air inlet 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.

[0060] 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 exhausted 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 resultant hot combustion products then expand through, and thereby drive, the high-pressure and low-pressure turbines 17, 19 before being expelled through the nozzle 20 to provide some thrust force. The high-pressure turbine 17 drives the high-pressure compressor 15 by means of a suitable connection 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.

[0061] 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. Radially to the outside of the sun gear 28 and meshing therewith are a plurality of planet gears 32 that are coupled to one another by a planet carrier 34. 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 supporting structure 24.

[0062] Note that the terms low-pressure turbine and low-pressure compressor as used herein may 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 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 can be referred to as a first, or lowest-pressure, compression stage.

[0063] 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 a person skilled in the art that more or fewer planet gears 32 can 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.

[0064] 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 annulus) 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 the ring gear 38 and the planet carrier 34 are both allowed to rotate.

[0065] It is self-evident that the arrangement shown in FIGS. 2 and 3 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 may be used for locating the gear box 30 in the gas turbine engine 10 and/or for connecting the gear box 30 to the gas turbine engine 10. As a further example, the connections (e.g. the linkages 36, 40 in the example of FIG. 2) between the gear box 30 and other parts of the gas turbine engine 10 (such as e.g. 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 gas turbine engine 10 (for example between the input and output shafts of the gear box and the fixed structures, such as the gear-box 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 than that shown by way of example in FIG. 2.

[0066] Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of types of gear box (for example star or epicyclic-planetary), supporting structures, input and output shaft arrangement, and bearing locations.

[0067] Optionally, the gear box may drive additional and/or alternative components (e.g. the intermediate-pressure compressor and/or a booster compressor).

[0068] Other gas turbine engines to which the present disclosure can be applied may have alternative configurations. For example, engines of this type 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 meaning that the flow through the bypass duct 22 has its own nozzle that is separate from 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 example described relates to a turbofan engine, the disclosure may be applied, for example, to any type of gas turbine engine, such as e.g. 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 may not comprise a gear box 30.

[0069] 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.

[0070] In FIG. 4, a first embodiment of a fundamentally rotationally symmetrical gear-box casing 50 is illustrated in an exploded view. In FIG. 4, only half of the gear-box casing 50 that is oriented toward the output side of the gear box 30 is illustrated. The other half of the gear-box casing 50, which is oriented toward the input side, is not illustrated here for reasons of overall clarity.

[0071] This gear-box casing 50 comprises the ring gear 38, which here comprises two toothed rings arranged in parallel. These toothed rings mesh with the planetary gears 32 running around in them, which by means of the drive shaft 41 are driven by the sun gear 28, which cannot be seen here.

[0072] The gear-box casing 50 is substantially constructed from three elements, which are in each case cylindrical. The ring gear 38 and the planetary gears 32 are arranged in the central region with a larger diameter. The two parts of the gear-box casing 50 that are arranged toward the output side or input side have in each case a smaller diameter. The part of the gear-box casing 50 that is not illustrated here is constructed substantially mirror-invertedly in relation to the part that is illustrated, i.e. the part toward the input side has the smaller diameter.

[0073] In principle, it is possible that the gear-box casing 50 is constructed as rotationally symmetrical, but not symmetrical in relation to the center plane of the gear box 30, i.e. different parts of the gear-box casing 50 may have different diameters.

[0074] The gear-box casing 50 has at least partially a region 51 comprising carbon-fiber reinforced plastic, the fibers 55 in this region 51 being arranged only in an angular range of +/40 to 50, in particular of +/42 to 48, here however +/45, in relation to the main axis of rotation 9 of the gear-box casing 50. This is illustrated in FIG. 5. FIG. 6 shows the same embodiment as FIG. 5, only from a different viewing style.

[0075] In principle, other fibers (metal, ceramic, synthetic, etc.) may also be used on their own or in combination.

[0076] This achieves a structure that is compliant in the axial and radial directions, and so the drive train is decoupled from movements of the gear box 30. The fibers 55 laid at an angle of substantially +/45 efficiently lead away torsional loads. The fibers 55 are in each case laid as monolayers, the fibers being incorporated in the matrix in particular without crossing, i.e. the fiber angle remains the same.

[0077] The angle is measured here by using a projection of the fiber winding onto the main axis of rotation 9. The region 55 should be understood here in the axial extent. In alternative embodiments, individual layers may be laid substantially at +/45, while other layers have a different angle.

[0078] In FIG. 9 and the following table, the dependence of the normalized flexural rigidity and the normalized torsional rigidity on the angle of the fibers is illustrated.

[0079] In the angular range with a 5 deviation either way from the 45 angle, in FIG. 8 only a minimal influence on the torsional rigidity, but a significant influence on the flexural rigidity can be seen. Consequently, in the case of the embodiment described, the flexural rigidity can be set within wide ranges without any influence on the torsional rigidity. The fiber volume content has a linear effect on both variables.

TABLE-US-00001 Normalized flexural Normalized torsional Fiber angle in rigidity rigidity +-40 136.30% 97.40% +-45 100.00% 100.00% +-50 78.30% 97.40% +-55 65.60% 89.70% +-60 58.30% 78.10%

[0080] Various methods may be used for producing such an embodiment, and these methods can also be combined with one another. Thus, e.g., a winding method, a braiding method, a TFP method (Tailored Fiber Process) or a combination of the methods may be used.

[0081] When using a braiding method, the fibers 55 may e.g. also be laid over steps. One example of a combination of methods is, e.g. the use of a TFP preform that is subsequently overwound or overbraided.

[0082] In the embodiment illustrated here, the gear-box casing 50 has an outside diameter of 1000 mm. Typically, such a gear-box casing 50 will transmit a torsional moment of 200 000 to 90 000 Nm, at a rotational speed of between 500 and 3000 rpm. These figures should be understood here as only given by way of example, since other design requirements also require different dimensioning of the gear-box casing 50.

[0083] In the embodiment illustrated, the gear-box casing 50, in particular the region 51 with fiber reinforced plastic, is of a substantially cylindrical configuration, with a circular cross section. Alternatively, it is also possible that part of the gear-box casing 50 is conically designed.

[0084] The embodiment of the gear-box casing 50 according to FIGS. 7 and 8 has a central region, which is formed as circular-cylindrical. Conical regions 58 are respectively arranged in relation to the input side 56 and the output side 57.

[0085] Illustrated in the side view of FIG. 8 are the windings of the fibers 55, the angles of which correspond to those of the first embodiment (FIGS. 4 to 6).

[0086] The fibers 55 run here in the conical regions 58, but also in the cylindrical region lying therebetween. Here, too, there is a carbon-fiber reinforced plastic, the fibers 55 in this region 51 likewise being arranged exclusively in an angular range of +/40 to 50, in particular of +/42 to 48, most particularly +/45, in relation to the main axis of rotation 9 of the shaft component 50.

[0087] These indications of the angle relate in one embodiment to the axial center of the conical region 58. The angle may become greater in the direction of a larger diameter and the angle may become smaller in the direction of a smaller diameter. The fiber volume content is at a maximum in the conical region, even independently of the angle of the fiber deposition.

[0088] It is self-evident that the invention is not limited to the embodiments described above and that various modifications and improvements may be made without departing from the concepts described herein. Except where mutually exclusive, any of the features can 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 that are described herein.

LIST OF REFERENCE SIGNS

[0089] 9 Main axis of rotation [0090] 10 Gas turbine engine [0091] 11 Core engine [0092] 12 Air inlet [0093] 14 Low-pressure compressor [0094] 15 High-pressure compressor [0095] 16 Combustion device [0096] 17 High-pressure turbine [0097] 18 Bypass thrust nozzle [0098] 19 Low-pressure turbine [0099] 20 Core thrust nozzle [0100] 21 Engine nacelle [0101] 22 Bypass duct [0102] 23 Fan [0103] 24 Stationary supporting structure [0104] 26 Shaft [0105] 27 Connecting shaft [0106] 28 Sun gear [0107] 30 Gear box [0108] 32 Planet gears [0109] 34 Planet carrier [0110] 36 Linkage [0111] 38 Ring gear [0112] 40 Linkage [0113] 41 Drive shaft [0114] 50 Gear-box casing [0115] 51 Region comprising fiber reinforced plastic [0116] 52 Form-fitting connection element [0117] 53 Supporting element, metal insert [0118] 55 Fibers [0119] 56 Input side [0120] 57 Output side [0121] 58 Conical region [0122] A Core air flow [0123] B Bypass air flow