Geared turbofan engine and splined shaft arrangement

Abstract

Geared turbofan engine having: - a fan level (13), - a fan shaft (14) via which the fan stage (13) is driven, - a turbine shaft (2), and - a planetary gear (100) which couples the fan shaft (14) and the turbine shaft (2) to each other, wherein - the planetary gear (100) has a sun gear (3) which rotates about an axis of rotation (11) of the geared fan engine (100) and is driven by the turbine shaft (2), wherein the axis of rotation (11) defines an axial direction of the geared fan engine (10), - the turbine shaft (2) forms an external spline (21) and the sun gear (3) forms an internal spline (31), and the external spline (21) and the internal spline (31) form a spline connection (7) between the turbine shaft (2) and the sun gear (3), - the splined shaft connection (7) has a toothed area (71) which is lubricated with oil, and - sealing means (9, 33) are provided which seal the oil in the toothed area (71) against axial leakage, wherein the sealing means (9, 33) comprise a sealing ring (9) which is arranged in a groove (22) extending in the circumferential direction of the turbine shaft (2), characterized in that - the sealing ring (9) is elastic, variable in its diameter and tensioned outwards, the sealing ring (9) resting with its radially outer circumferential surface on an inner circumferential surface (32) of the sun gear (3) and - the sealing ring (9) and / or the groove (22) are designed such that oil can be introduced into the toothing area (71) through a radial gap (55) under the sealing ring (9).

Description

[0001] The invention relates to a geared turbofan engine according to the preamble of patent claim 1 and a splined shaft arrangement.

[0002] It is known that the gearing area of ​​a splined shaft connection between the drive shaft and the sun gear of a planetary gear in a geared turbofan engine is lubricated with oil. This requires ensuring a sufficient oil level in the gearing area. This requires, on the one hand, sealing the gearing area with sealing elements. On the other hand, it is necessary to introduce oil into the gearing area during operation. Another challenge is ensuring that the sealing elements are not damaged during assembly.

[0003] From DE 10 2016 204 070 A1 a splined shaft connection is known in which a sealing ring is arranged at one end of the splined shaft connection in a seal housing groove.

[0004] US 2013 / 0 336 791 A1 discloses a generic geared turbofan engine.

[0005] JP 2017-166 703 A discloses a sealing ring for hydraulic devices used in automatic transmissions for motor vehicles. The sealing ring is designed to be inserted into a matching groove on a shaft.

[0006] EP 0 587 153 A2 discloses a low-pressure compressor in which a sealing ring forms a seal between an inlet housing and another housing section, thus enabling the formation of a pressure difference between two different chambers.

[0007] The present invention is based on the object of providing a geared turbofan engine and a spline shaft assembly in which an effective seal is provided to ensure a sufficient oil level in the toothing area of ​​the spline connection between the drive shaft and the sun gear.

[0008] This object is achieved by a geared turbofan engine having the features of claim 1 and a splined shaft arrangement having the features of claim 16. Embodiments of the invention are specified in the subclaims.

[0009] A first aspect of the invention then considers a geared turbofan engine comprising a fan stage, a fan shaft via which the fan stage is driven, a turbine shaft, and a planetary gear, wherein the planetary gear couples the fan shaft and the turbine shaft to one another. The planetary gear comprises a sun gear that rotates about an axis of rotation of the geared turbofan engine and is driven by the turbine shaft, wherein the axis of rotation defines an axial direction of the geared turbofan engine. The axial direction is defined as being directed from the fan to the turbine of the engine. The turbine shaft forms an external spline, and the sun gear forms an internal spline, wherein the external spline and the internal spline form a spline connection between the turbine shaft and the sun gear. The spline connection has a gearing region that is lubricated with oil.Sealants are also provided to prevent the oil from leaking axially in the gearing area.

[0010] The sealing means are provided with an elastic, variable-diameter, outwardly tensioning sealing ring arranged in a groove extending in the circumferential direction of the turbine shaft. The sealing ring rests with its radially outer circumferential surface against an inner circumferential surface of the sun gear, which forms the sun gear axially adjacent to or laterally to the internal spline.

[0011] The fact that the sealing ring is elastic and stretches outwards means that, when installed, the elasticity of the sealing ring is such that the sealing ring tends to increase its diameter. The natural diameter of the sealing ring corresponds to the original shape of the sealing ring, which the sealing ring assumes when no forces act on it. If the sealing ring assumes a diameter smaller than its natural diameter, it generates a force on the surrounding element, forcing it to the smaller diameter.

[0012] According to one embodiment, the sealing ring is made of a hard material. For example, the sealing ring is made of steel, for example a steel with a Vickers hardness HV in the range 400 HV 10 to 600 HV 10, or of a cast material, e.g. cast iron. According to an alternative embodiment, the sealing ring is made of a hard plastic, for example polytetrafluoroethylene (PTFE) or a polyamide-imide (PAI), e.g. Torlon®. One embodiment provides that the plastic is wear- and age-resistant. According to one embodiment, the hardness of the sealing ring is lower than the hardness of the material from which the turbine shaft and the sun gear or the splined shaft connection are formed. Using a sealing ring made of a hard material enables a long service life of the sealing ring. This saves maintenance time and costs.In particular, the use of a sealing ring made of a hard material prevents the sealing ring from becoming brittle over time, losing functionality, or even breaking in the worst case. If the sealing ring is naturally brittle, the material is selected in such a way that the material does not become brittle or begin to age over time.

[0013] The inventive solution provides an arrangement in which, due to the elastic design of the sealing ring with a variable diameter, the gap extending axially adjacent to the toothed area of ​​the splined shaft connection between the sun gear and the turbine shaft is securely sealed. The elastic design and outwardly directed tension of the sealing ring ensures that the sealing ring rests under tension and thus tightly against the adjacent circumferential surface of the sun gear. At the same time, the elastic sealing ring with a variable diameter enables simplified assembly, as it is possible to compress the sealing ring to smaller diameters during assembly without damaging the ring.

[0014] It should be noted that the variable diameter of the sealing ring is an inherent property of the sealing ring. This feature should not be understood to mean that the diameter of the sealing ring can still be changed or adjusted after it has been fully installed in the geared turbofan engine.

[0015] According to the invention, it is further provided that the sealing ring and / or the groove are designed such that oil can be introduced into the gearing area through a radial gap below the sealing ring. The radial gap extends between the sealing ring and the base or root circle plane of the gearing of the turbine shaft. This makes it possible to continuously supply oil to the gearing area of ​​the spline connection during operation, ensuring a sufficient oil level in the gearing area at all times.

[0016] One embodiment of the invention provides that the sealing ring has two ends that are adjacent to one another and overlap each other, with the degree of overlap determining the diameter of the sealing ring. This applies regardless of whether the inner diameter or the outer diameter of the sealing ring is considered. The above statement thus applies to both the inner diameter and the outer diameter. This also applies to other statements regarding the diameter, unless a distinction is made between inner diameter and outer diameter.

[0017] One embodiment provides that the ends of the sealing ring overlap freely and thus form an extension with an axial contact surface, with the extensions abutting one another at their axial contact surfaces. A stop or the like that limits the expansion of the sealing ring is not provided in this embodiment.

[0018] An alternative embodiment provides that the ends of the sealing ring overlap each other, each forming an extension with an axial contact surface and an axial projection. The degree of overlap of the ends has a maximum and a minimum, and the minimum degree of overlap is defined by the axial projections of the two extensions, which engage with each other at the minimum degree of overlap. The expansion of the sealing ring is thus limited by said projections in this embodiment. At the maximum degree of overlap, the diameter of the sealing ring is minimal, and at the minimum degree of overlap, the diameter of the sealing ring is maximum.

[0019] One embodiment provides for the sealing ring to have concave indentations extending in the radial direction on its radial inner circumferential surface. The indentations are, for example, arc-shaped and evenly distributed over the inner circumference of the sealing ring. The indentations allow oil to be introduced into the gearing area through the radial gap extending between the indentations and the turbine shaft. The oil is sprayed onto the gap, for example, from the side.

[0020] One embodiment of the invention provides that the groove in which the sealing ring is arranged is formed in an extension region of the external spline toothing of the turbine shaft, which extends in the axial direction beyond the toothing region. According to this embodiment, the external spline toothing of the turbine shaft thus forms a region that extends axially adjacent to the toothing region and in this respect represents an extension region of the external spline toothing. It can be provided that the groove formed in the extension region, in which the sealing ring is arranged, has a smaller radial depth than the external spline toothing of the outer shaft. This also creates a radial gap beneath the sealing ring, through which oil can be introduced into the toothing region. Oil is sprayed onto the gap, for example, from the side.

[0021] It should be noted that the external spline of the turbine shaft in the extension area where the groove is formed does not necessarily have the same toothing as in the toothing area of ​​the splined shaft connection. For example, it can be provided that the external spline has a smaller number of teeth in the extension area than in the toothing area. Only enough teeth must be provided to allow the sealing ring to be securely positioned axially in the groove. A minimum of three teeth is sufficient for this. Of course, it can also be provided that the toothing in the extension area is designed in the same way as in the toothing area.

[0022] A further embodiment of the invention provides that the sealing means which seal the oil in the toothing region against axial leakage have, in addition to the sealing ring, a further sealing element which is arranged or formed axially opposite the sealing ring and thus on the axially front side of the toothing region. For example, it can be provided that the further sealing element is formed by a further sealing ring which is formed integrally with the sun gear or is fastened thereto. According to one embodiment, the further sealing ring is arranged and formed such that it forms a gap to the turbine shaft through which oil can be introduced into the toothing region in the axial direction. According to this embodiment, oil can be introduced, for example sprayed, into the toothing region of the splined shaft connection from the axially front side.

[0023] A further embodiment of the invention provides a means that interacts with the sealing ring and couples the rotation of the sealing ring to the rotation of the turbine shaft. This means that the sealing ring rotates in synchronization with the drive shaft or is circumferentially coupled to the turbine shaft. This means, in particular, that when the turbine is shut down, the sealing ring is also decelerated and is not further rotated by the sun gear due to its contact with the sun gear.

[0024] According to one embodiment, said means is formed by a pin connected to the turbine shaft, which extends radially and passes through a corresponding opening in the sealing ring. According to another embodiment, said means is formed by an axial extension of the sealing ring, which engages the external spline of the turbine shaft. In both cases, the sealing ring is coupled to the turbine shaft via said means.

[0025] A further embodiment of the invention provides that the sun gear has an axially rear, radially extending end face and forms a chamfer radially on the inside of the axially rear end face, which is aligned and dimensioned such that when the sun gear is pushed onto the turbine shaft for assembly purposes, the sealing ring comes to rest on the chamfer of the sun gear, the sealing ring is compressed by the shape of the chamfer during further axial displacement of the sun gear in the radial direction and finally rests under tension with its radially outer circumferential surface on the inner circumferential surface of the sun gear.

[0026] This embodiment of the invention enables effective and secure assembly and placement of the sealing ring through the interaction of, on the one hand, a chamfer on one end face of the sun gear and, on the other hand, the elastic, variable-diameter, outwardly tensioning sealing ring. The sealing ring is compressed by the chamfer during the assembly movement. After assembly is complete, the sealing ring rests under tension against the facing circumferential surface of the sun gear. The variable diameter of the sealing ring enables the realization of two functions. Firstly, effective assembly is enabled, minimizing the risk of damage to the sealing ring and allowing "blind" assembly in the sense that visual tracking of the sealing ring during assembly is not necessary.On the other hand, the variable diameter of the sealing ring enables the provision of an effective seal in which the sealing ring lies tightly against the mating surface (the facing circumferential surface of the sun gear).

[0027] The planetary gear of the geared turbofan engine can have additional elements: - a plurality of planetary gears driven by the sun gear, - a ring gear with which the plurality of planetary gears mesh, and - a plurality of planetary pins, wherein each planetary pin is arranged in a planetary gear and the planetary pin and the planetary gear form a lubricated bearing, wherein the planetary pins are coupled to a torque carrier and the torque carrier is coupled to the fan shaft.

[0028] In a further aspect of the invention, the invention relates to a splined shaft arrangement comprising: - a drive shaft having external splines, - an output element having an internal spline and driven by the drive shaft, wherein - the external spline and the internal spline form a splined connection between the input shaft and the output element, - the splined shaft connection has a toothed area that is lubricated with oil, and - Sealing agents are provided to prevent the oil from leaking axially in the gearing area.

[0029] It is provided that the sealing means comprise an elastic sealing ring with a variable diameter and an outwardly tensioning ring, which rests with its radially outer circumferential surface against an inner circumferential surface of the output element.

[0030] It is further provided that the sealing ring and / or the groove are designed such that oil can be introduced into the toothing area through a radial gap under the sealing ring.

[0031] According to one embodiment, the external spline of the drive shaft extends axially beyond the spline region and forms an extension region of the external spline axially adjacent to (or next to) the spline region. The sealing ring is arranged in a groove extending in the circumferential direction of the drive shaft, wherein the groove is formed in the extension region in the external spline of the drive shaft.

[0032] A further embodiment provides that the sealing ring has two ends that are adjacent to one another and overlap each other, with the degree of overlap determining the diameter of the sealing ring. Further embodiments of the splined shaft arrangement have features corresponding to the features specified in claims 3-15.

[0033] The splined shaft arrangement according to the invention is formed, for example, in a planetary gear which is, for example, part of a geared turbofan engine.

[0034] It should be noted that the present invention, insofar as it relates to an aircraft engine, is described with reference to a cylindrical coordinate system having the coordinates x, r and φ. Here, x indicates the axial direction, r the radial direction and φ the angle in the circumferential direction. The axial direction is defined by the axis of rotation of the planetary gear, which is identical to a machine axis of a geared turbofan engine in which the planetary gear is arranged. Starting from the x-axis, the radial direction points radially outwards. Terms such as "in front of", "behind", "front" and "rear" refer to the axial direction or the flow direction in the engine in which the planetary gear is arranged. Terms such as "outer" or "inner" refer to the radial direction.

[0035] The invention is explained in more detail below with reference to the figures of the drawing using several exemplary embodiments. They show: Fig. 1 is a simplified schematic sectional view of a geared turbofan engine in which the present invention can be implemented; Fig. 2 a sectional view of elements of a planetary gear unit designed for use in a geared turbofan engine according to Fig. 1 is suitable; Fig. 3 shows, in a partially sectioned view, an embodiment of a splined shaft connection between a drive shaft and a sun gear, wherein the splined shaft connection comprises an elastic sealing ring of variable diameter which is arranged in a groove formed in the drive shaft; Fig. 4 the spline connection of the Fig. 3 in a partially sectioned, perspective view; Fig. 5a a first embodiment of the sealing ring of the Fig. 3 and Fig. 4; Fig. 5b the detail A of the embodiment of the Fig. 5a; Fig. 6a a second embodiment of the sealing ring of the Fig. 3 and Fig. 4; Fig. 6b the detail B of the embodiment of the Fig. 6a; Fig. 7 a third embodiment of the sealing ring of the Fig. 3 and Fig. 4, wherein the sealing ring has indentations on its inner circumference; Fig. 8a a first process step for assembling the sun gear of the Fig. 3 and Fig. 4 on the drive shaft, wherein the sealing ring is placed in a groove of the turbine shaft; Fig. 8b a second process step for assembling the sun gear of the Fig. 3 and Fig. 4 on the drive shaft, the sealing ring coming into contact with a chamfer on an axial rear end face of the sun gear; Fig. 8c a third process step for assembling the sun gear of the Fig. 3 and Fig. 4 on the drive shaft, the sealing ring having been compressed by the chamfer and having reached its final position; Fig. 9 schematically shows the introduction of oil from the axial rear side into the toothing area of ​​the spline connection of the Fig. 3 and Fig. 4, wherein the oil is introduced through a gap formed under the sealing ring; Fig. 10 a view from behind the Fig. 9 in the area of ​​the sealing ring, showing the radial gap between the sealing ring and the drive shaft; Fig. 10a a view corresponding to the Fig. 10 showing the radial gap between the sealing ring and the drive shaft, wherein the external spline toothing forms a reduced number of teeth in an extension region; Fig. 11 schematically shows the introduction of oil from the axial front side into the toothing area of ​​the spline connection of the Fig. 3 and Fig. 4, wherein the oil is introduced through a gap formed between an axially forward sealing ring connected to the sun gear and the drive shaft; Fig. 12 shows schematically in longitudinal section an embodiment of a splined shaft connection between a drive shaft and a sun gear, in which a pin connected to the drive shaft is provided which couples the sealing ring to the drive shaft; Fig. 13 schematically shows the arrangement of pin and sealing ring of the Fig. 12 in a view from above; and Fig. 14 shows schematically in longitudinal section an embodiment of a splined shaft connection between a drive shaft and a sun gear, in which the sealing ring forms an axial extension which engages in the external spline teeth of the drive shaft.

[0036] The Fig. Figure 1 shows a geared turbofan engine 10 with a rotational axis 11, intended for use in aircraft. In the direction of axial flow, the geared turbofan engine 10 has, in series, an air inlet 12, a fan stage 13 (in principle, more than one fan stage 13 is also possible), a fan shaft 14, a gearbox 100, a medium-pressure compressor 15, a high-pressure compressor 16, a combustion device 17, a high-pressure turbine 18, a medium-pressure turbine 19, and a nozzle 20. A fan casing 210 surrounds the fan stage 13 and defines the air inlet 12.

[0037] The geared turbofan engine 10 basically operates in a conventional manner, with air entering the air intake 12 being accelerated by the fan stage 13. Two airstreams are generated: a first stream enters the intermediate-pressure compressor 15, and a second airstream flows through a bypass duct 220, with the second airstream providing the majority of the thrust of the geared turbofan engine 10. The intermediate-pressure compressor 15 compresses the incoming airstream before it enters the high-pressure compressor 16, where further compression occurs. The compressed air exiting the high-pressure compressor 16 is fed into the combustor 17, where it is mixed with fuel, and the mixture is then combusted. The hot combustion gases are expanded in the high-pressure turbine 18 and the intermediate-pressure turbine 19 before exiting through the nozzle 200, thus providing additional thrust.

[0038] Behind the fan stage 13, the geared turbofan engine 10 thus forms a bypass duct 220 and a primary flow duct. The primary flow duct runs through the core engine (gas turbine), which includes the intermediate-pressure compressor 15, the high-pressure compressor 16, the combustion device 17, the high-pressure turbine 18, and the intermediate-pressure turbine 19. During operation of the geared turbofan engine 10, the bypass duct 220 directs air drawn in by the fan stage 13 past the core engine.

[0039] The high-pressure turbine 18 and the intermediate-pressure turbine 19 drive the high-pressure compressor 16 and the intermediate-pressure compressor 15, respectively, via shaft devices. A medium-pressure shaft drives the fan stage 13 via the gearbox 100. The gearbox 100 is designed as a reduction gear that reduces the speed of the fan stage 13 compared to the medium-pressure compressor 15 and the medium-pressure turbine 19. In the illustrated embodiment, the gearbox 100 is a planetary gear with a static ring gear 5 and rotating planet gears 4 that rotate within the ring gear 5. The gearbox 100 is driven via a sun gear 3 that is coupled to the medium-pressure shaft. In the illustrated embodiment, the output is via a torque carrier 70 that is coupled to the planet gears 4. The torque carrier 70 is coupled to the fan shaft 14, which drives the fan stage 13.

[0040] In principle, other embodiments of the transmission 100 are also possible, wherein, for example, the ring gear 5 can be designed to be movable, so that the output takes place via the ring gear 5.

[0041] The design of the geared turbofan engine 10 according to the Fig. 1 is merely an example. In particular, the arrangement of the shafts can also be chosen differently, although two- or three-shaft arrangements are generally possible. For example, a three-shaft arrangement can alternatively be provided, comprising a low-pressure shaft connecting the low-pressure turbine to the fan, a medium-pressure shaft connecting the medium-pressure turbine to the medium-pressure compressor, and a high-pressure shaft connecting the high-pressure turbine to the high-pressure compressor. The fan stage 13 is connected to the low-pressure shaft via a gearbox.

[0042] The described components share a common rotational or machine axis, the rotational axis 11. The rotational axis 11 defines an axial direction of the drive unit 10. A radial direction of the drive unit 10 runs perpendicular to the axial direction.

[0043] The Fig. 2 shows an embodiment of the planetary gear 100 of the geared turbofan engine 10 of the Fig. 1 in a sectional view. The planetary gear 100 comprises a sun gear 3, which is driven by a drive shaft or sun shaft 2. The drive shaft 2 is the medium pressure shaft of the Fig. 1 or, more generally, a turbine shaft. The sun gear 3 and the drive shaft 2 rotate around the rotational axis 11. The rotational axis of the planetary gear 100 is identical to the machine axis of the geared turbofan engine 10.

[0044] The planetary gear 100 further comprises a plurality of planetary gears 4, of which in the sectional view of the Fig. 2. The sun gear 3 drives the majority of the planet gears 4, with one tooth of the sun gear 3 meshing with one tooth of the planet gear 4.

[0045] The planet gear 4 is hollow cylindrical and forms an outer surface and an inner surface. The planet gear 4 rotates - driven by the sun gear 3 - about a rotational axis 111 that runs parallel to the rotational axis 11. The outer surface of the planet gear 4 forms a toothing that meshes with the toothing of a ring gear 5. The ring gear 5 is stationary, i.e., non-rotating. The planet gears 4 rotate due to their coupling with the sun gear 3 and, in doing so, move along the circumference of the ring gear 5. The rotation of the planet gears 4 along the circumference of the ring gear 5 and, in doing so, around the rotational axis 111 is slower than the rotation of the drive shaft 2, thereby providing a reduction ratio.

[0046] The planetary gear 4 has a centered axial opening adjacent to its inner circumferential surface. A planetary pin 6, which also has an axial bore 60 itself, is inserted into the opening. The planetary pin 6 and the planetary gear 4 form a bearing 65, for example, a rolling bearing or a plain bearing, on their mutually facing surfaces.

[0047] The Fig. Figure 2 further shows a front carrier plate 81 and a rear carrier plate 82. The planetary pin 6 is attached, for example, bolted or welded, to the front carrier plate 81 and the rear carrier plate 82. For example, the front carrier plate 81 is connected to a torque carrier 70, which is coupled to the fan shaft.

[0048] For lubricating the bearing 65 between the planetary pin 6 and the planetary gear 4, an oil supply device is provided which comprises an oil supply channel 62 through which oil from a circulating oil system is fed into lubricating film openings 61 in the planetary pin 6.

[0049] In the context of the present invention, the coupling of the sun gear 3 with the drive shaft 2 is important with regard to a splined shaft connection 7 implemented for this purpose.

[0050] The Fig. 3 and Fig. 4 show an embodiment of a splined shaft connection 7 for coupling a drive shaft 2 to a sun gear 3. Even if the invention is described by way of example with reference to a splined shaft connection that couples a drive shaft to a sun gear of a planetary gear, the principles of the present invention are applicable in a corresponding manner to any splined shaft arrangement in which a drive shaft and an output element are connected to one another via a splined shaft connection.

[0051] According to the Fig. 3 and Fig. 4, the drive shaft 2, which is a turbine shaft in the illustrated context, comprises an external spline 21. Correspondingly, the sun gear 3 comprises an internal spline 31. The external spline 21 and the internal spline 31 form a spline connection 7. The spline connection 7 comprises a spline region 71 in which the keys or keyways of the internal spline and the external spline engage. The spline region 71 is lubricated with oil. To prevent the oil from axially escaping the spline region, two sealing rings 9, 33 are provided to axially seal the spline region 71.

[0052] The external spline 21 of the drive shaft 2 forms two axially spaced sections or regions 211, 212. The first region 211, together with the internal spline 31 of the sun gear 3, forms the spline region 71 of the spline connection 7. The second region 212 extends in the axial direction beyond the spline region 71 and forms an extension region of the external spline 21, axially adjacent to the spline region 71.

[0053] In the region 212, which forms the extension region, a groove 22 is formed, which runs in the circumferential direction of the drive shaft 2. In the groove 22, and thus in the region of the region 212, one sealing ring 9 is arranged. In the illustrated embodiment, the toothing in the second region 212 is identical to the toothing in the first region 211, in particular the same number of teeth are provided in the circumferential direction. However, this is not necessarily the case. In principle, it can alternatively be provided that the toothing in the second region 212 is designed differently from the toothing in the first region 211, in particular having a smaller number of teeth. This can reduce the manufacturing effort. In this case, enough teeth are required in the second region 212 to define the groove 22 and the sealing ring 9 is axially securely positioned by the groove 22. An exemplary embodiment of this is described with reference to the Fig. 10a explained.

[0054] As regards the Fig. 5a, Fig. 5b, Fig. 6a, Fig. 6b will be explained in more detail, the sealing ring 9 is designed to be elastic and to stretch outwards, wherein the sealing ring 9 has a variable diameter.

[0055] The sealing ring 9 rests with its radially outer circumferential surface against an inner circumferential surface 32 of the sun gear 3, which forms the sun gear 3 axially adjacent to the internal spline 31. Due to the design of the sealing ring 9 as an outwardly tensioning surface, the sealing ring 9 rests tightly and with a radial force against the circumferential surface 32 of the sun gear 3.

[0056] The additional sealing ring 33 is arranged axially in front of the gearing area 71. This sealing ring 33 is formed integrally with the sun gear 3 or is attached to it. The two sealing rings 9, 33 ensure a sufficiently high oil level in the gearing area 71.

[0057] The Fig. 3 and Fig. 4 further show bellows-like bulges of the drive shaft 2, which serve to make it flexible.

[0058] With regard to the assembly of the splined shaft connection 7, it should be noted that the planetary gear with the sun gear 3 is pushed onto the drive shaft 2 during assembly. This means that the sealing ring 9 is not visible during assembly and cannot be inspected after assembly. To ensure a safe, precise and damage-free assembly of the sealing ring 9, the sun gear 3 has a chamfer 35 on its axially rear end face 34 radially inward, with which the sealing ring 9, which has a variable diameter, interacts during assembly, as can be seen from the Fig. 8a- 8c is explained.

[0059] The Fig. 5a, Fig. 5b shows a first embodiment of a sealing ring 9 with a variable diameter. The sealing ring 9 has a radially inner circumferential surface 91 and a radially outer circumferential surface 92. As explained, the radially outer circumferential surface 92 borders the inner circumferential surface 32 of the sun gear 3. Both circumferential surfaces 91, 92 are cylindrical in the illustrated embodiment, but not necessarily so.

[0060] In order to realize a variable diameter of the sealing ring 9, the sealing ring 9 forms a separation point and at this a movable area A, which in the Fig. 5b is shown enlarged in a top view. According to this diagram, the movable region A is formed by two ends 93, 94 of the sealing ring 9, which are adjacent to each other and overlap each other, with the degree of overlap determining the diameter of the sealing ring. The smaller the degree of overlap, the larger the diameter of the sealing ring 9.

[0061] To provide a movable overlap, each end 93, 94 has an extension 931, 941 that occupies half the width of the sealing ring 9. Each extension 931, 941 forms an axial contact surface 932, 942 that abut against each other and along which the ends 93, 94 of the sealing ring 9 are movable relative to each other. Fig. Figure 5b shows the situation where the degree of overlap is maximum and, accordingly, the diameter of the sealing ring 9 is minimum. At the maximum degree of overlap, the end faces 933, 943 of the ends 93, 94 abut the respective other end 94, 93.

[0062] The minimum degree of overlap and maximum diameter of the sealing ring 9 are determined by the original shape of the sealing ring 9, i.e., the shape the sealing ring assumes when no forces act on it. According to one embodiment, this original shape is selected such that the extensions 931, 941 overlap just slightly, so that when forces act on the sealing ring 9 that lead to a reduction in the diameter of the sealing ring 9, the extensions 931, 941 are guided in a defined manner along their contact surfaces 932, 942. In principle, however, it is also conceivable for the extensions 931, 932 to be spaced apart in the circumferential direction in the original shape.

[0063] The sealing ring 9 is designed to be tensioned outwards, ie it tries to assume its largest possible diameter.

[0064] The Fig. 6a, Fig. 6b show an alternative design of a sealing ring 9, which also has a separation point and forms a displaceable area B at this point. The displaceable area B is in the Fig. 6b is shown in an enlarged view from above. The design of the Fig. 6a, Fig. 6b differs from the design of the Fig. 5a, Fig. 5b in that an axial projection 935, 945 is formed on each of the extensions 931, 932, which results in a minimum overlap and thus a maximum diameter of the sealing ring 9 being achieved when the axial projections 935, 945 engage with each other. In this embodiment, a minimum diameter and a maximum diameter of the sealing ring 9 are defined. The sealing ring 9 is designed to be spanned outwards, i.e., it attempts to assume the maximum diameter.

[0065] The Fig. Figure 7 shows a further embodiment of a sealing ring 9. The sealing ring 9 is characterized in that it has concave indentations 96 extending in the radial direction on its radially inner circumferential surface 91. The indentations 96 are, for example, arc-shaped and are regularly distributed over the inner circumference of the sealing ring 9. These indentations 96 provide a means of transporting oil between the sealing ring 9 and the drive shaft into the toothing area of ​​the spline connection, as can be seen from the Fig. 9 and Fig. 10 is explained. In the Fig. 7, the variability of the diameter of the sealing ring 9 is not shown separately. This can be adjusted according to the Fig. 5a, Fig. 5b, Fig. 6a, Fig. 6b must be trained.

[0066] The Fig. 8a to 8c show the method for mounting the planetary gear or the sun gear 3 of the planetary gear on the drive shaft 2. The sun gear 3 is pushed onto the drive shaft 2 in the axial direction.

[0067] According to the Fig. 8a, the sealing ring 9 is first placed in the groove 22 formed in the extension area 212 of the external spline 21. In the following, according to the Fig. 8b the sun gear is pushed in the axial direction onto the drive shaft 2. On the one hand, the external spline 21 of the drive shaft 2 engages with the internal spline 31 of the sun gear 3. On the other hand, during the axial displacement of the sun gear 3, the sealing ring 9 comes into contact with the chamfer 35 formed radially inward on the axially rear end face 34. The chamfer 35 is aligned and dimensioned in such a way, ie has such a radial height and bevel, that the sealing ring 9 is compressed by the shape of the chamfer 35 upon further displacement of the sun gear 3 in the radial direction.

[0068] Fig. 8c shows the sealing ring 9 in the finished assembly position, in which it rests with tension on the inner circumferential surface 32 of the sun gear 3.

[0069] Due to the interaction of the chamfer 35 with the elastic, variable-diameter sealing ring 9, the sealing ring can be installed "blindly," i.e., without the possibility of visual observation during assembly, safely and without the risk of damage. At the same time, the sealing ring's outwardly tensioning design forces the sealing ring against the opposing surface 32 of the sun gear 3, thus achieving a high-quality and reliable sealing function.

[0070] The Fig. Figure 9 shows an example of introducing oil into the toothed area 71 of the splined shaft connection. The basic structure corresponds to that of Fig. 3 and Fig. 4, to which reference is made in this respect. Additionally shown in the Fig. 9, on the one hand, an oil level 8, which is formed with a height h between the axial front sealing ring 33 and the axial rear sealing ring 9 in the toothing area 71. Since the oil experiences a radially outward force during operation due to the centrifugal force, the oil level 8 is formed adjacent to the sun gear 3.

[0071] The oil level 8 must not drop and must therefore be replenished with new oil continuously or at defined times. This is achieved via an oil jet 52, which is sprayed via an applicator 50 from behind, i.e., counter to the axial direction, onto a radial gap 55 formed beneath the sealing ring 9. The oil reaches the toothing area 71 via this gap 55, as schematically illustrated by the arrow. This is possible because the external spline extends continuously from the groove 22 to the toothing area 71.

[0072] The formation of the gap 55 is determined with respect to the Fig. 10 is explained in more detail. This shows, in a rear view from radially outside to radially inside, the sun gear 3, the sealing ring 9, the external spline in its extension region 212, and the drive shaft 2. To realize the gap 55 between the sealing ring 9 and the drive shaft 2, two designs can be provided, which can be realized individually or both together.

[0073] According to the first embodiment, the sealing ring 9 is designed according to the Fig. 7, i.e., it has arcuate indentations 96 on its inner circumference. These indentations 96 form or enlarge a gap 551 between the sealing ring 9 and the drive shaft 2 (or between the sealing ring 9 and the root circle plane of the external spline 21 of the drive shaft 2). According to the second embodiment, the groove 22 has a smaller radial depth than the external spline 21 of the drive shaft 3. Accordingly, even when the sealing ring 9 is fully inserted into the groove 22, a gap 552 is formed between the radially inner circumferential surface 91 (cf. Fig. 5a, Fig. 6a, Fig. 7) of the sealing ring 9 and the root circle plane of the external spline 71.

[0074] The gap 55 of the Fig. 9 is thus composed of the gap 551 and / or the gap 552 of the Fig. 10 together.

[0075] The Fig. 10a shows an embodiment in which the external spline toothing in its extension region 212 differs from the toothing in the first region 211 (cf. Fig. 3 and Fig. 4). Thus, the external spline in the embodiment of the Fig. 10a has only three teeth in its extension area 212, which are evenly distributed along the circumference. One of the teeth is in the Fig. 10a. There are still sufficient teeth present to define the groove 22 and to securely position the sealing ring 9 axially through the groove 22.

[0076] As in the example, the Fig. 10, the groove 22 has a smaller radial depth than the external spline of the drive shaft 3. Accordingly, even if the sealing ring 9 is fully inserted into the groove 22, a gap 552 is present between the radially inner circumferential surface 91 of the sealing ring 9 and the root plane of the external spline. Alternatively or additionally, it can be provided that the sealing ring 9 is Fig. 7 has 91 curved indentations on its inner circumference (in the Fig. 10a not shown separately).

[0077] The Fig. Figure 11 shows an alternative embodiment for introducing oil into the toothed area 71 of the splined shaft connection. Unlike the Fig. 9, an oil jet 53 is supplied from the front, i.e., in the axial direction, via an applicator 51 to maintain the oil level 8. The oil jet 53 is introduced via a gap 56 into the toothed area 71 formed between the front sealing ring 33 connected to the sun gear 3 and the drive shaft 2.

[0078] One embodiment of the invention provides that the sealing ring 9 is coupled in the circumferential direction to the drive shaft 2 so that they have the same rotational speed. A first embodiment of this is shown in the Fig. 12 and Fig. 13 And a second example of this is shown in the Fig. 14.

[0079] After that, according to the Fig. 12 and Fig. 13, a pin 27 is connected to the drive shaft 2, extending in the radial direction and passing through an opening 98 formed in the sealing ring 9. As a result, the sealing ring 9 is accelerated when the drive shaft accelerates, and decelerated when the drive shaft decelerates. Rotation of the sealing ring 9 relative to the drive shaft 2, however, is prevented.

[0080] The Fig. 14 provides for the realization of such functionality that the sealing ring 9 forms an axial extension 97 which engages in the region 212 of the external spline 21, whereby the sealing ring 9 is coupled to the drive shaft 2 in the circumferential direction and with regard to its rotational movement.

[0081] The present invention is not limited in its design to the exemplary embodiments described above. For example, the illustrated design of the sealing element 9 is to be understood merely as an example.

[0082] Furthermore, it should be noted that the features of the individual described embodiments of the invention can be combined with one another in various combinations. Where ranges are defined, these include all values ​​within these ranges as well as all subranges that fall within a range.

Claims

[1] Geared turbofan engine, which has: - a fan level (13), - a fan shaft (14) via which the fan stage (13) is driven, - a turbine shaft (2), and - a planetary gear (100) which couples the fan shaft (14) and the turbine shaft (2) to each other, wherein - the planetary gear (100) has a sun gear (3) which rotates about an axis of rotation (11) of the geared fan engine (100) and is driven by the turbine shaft (2), wherein the axis of rotation (11) defines an axial direction of the geared fan engine (10), - the turbine shaft (2) forms an external spline (21) and the sun gear (3) forms an internal spline (31), and the external spline (21) and the internal spline (31) form a spline connection (7) between the turbine shaft (2) and the sun gear (3), - the splined shaft connection (7) has a toothed area (71) which is lubricated with oil, and - sealing means (9, 33) are provided which seal the oil in the toothed area (71) against axial leakage, wherein the sealing means (9, 33) comprise a sealing ring (9) which is arranged in a groove (22) extending in the circumferential direction of the turbine shaft (2), characterized by , that - the sealing ring (9) is elastic, variable in its diameter and tensioned outwards, the sealing ring (9) resting with its radially outer circumferential surface on an inner circumferential surface (32) of the sun gear (3) and - the sealing ring (9) and / or the groove (22) are designed such that oil can be introduced into the toothing area (71) through a radial gap (55) under the sealing ring (9). [2] Geared turbofan engine according to claim 1, characterized bythat the sealing ring (9) has two ends (93, 94) which are adjacent to one another and overlap one another, the degree of overlap determining the diameter of the sealing ring (9). [3] Geared turbofan engine according to claim 2, characterized by that the ends (93, 94) of the sealing ring (9) overlap freely and thereby each form an extension (931, 941) with an axial contact surface (932, 942), wherein the extensions abut one another at their axial contact surfaces. [4] Geared turbofan engine according to claim 2, characterized byin that the ends (93, 94) of the sealing ring (9) overlap one another and in doing so each form an extension (931, 941) with an axial contact surface (932, 942) and an axial projection (935, 945), wherein the degree of overlap of the ends (93, 94) has a maximum and a minimum, and wherein the minimum degree of overlap is defined by the axial projections (935, 945) of the two extensions (931, 941) which engage with one another at the minimum degree of overlap. [5] Geared turbofan engine according to one of the preceding claims, characterized by that the sealing ring (9) has concave indentations (96) extending in the radial direction on its radially inner peripheral surface (91). [6] Geared turbofan engine according to claim 5, characterized by that the indentations (91) are arc-shaped and are regularly distributed over the inner circumference of the sealing ring (9). [7] Geared turbofan engine according to one of the preceding claims, characterized by that the groove (22) is formed in an extension region (212) of the external spline toothing (21) of the turbine shaft (2), which extends in the axial direction beyond the toothing region (71). [8] Geared turbofan engine according to claim 7, characterized by that the groove (22) formed in the extension region (212), in which the sealing ring (9) is arranged, has a smaller radial depth than the external spline toothing (21) of the drive shaft (2). [9] Geared turbofan engine according to one of the preceding claims, characterized by that the sealing means which seal the oil in the toothed region (71) against axial leakage have, in addition to the sealing ring (9), a further sealing element (33) which is arranged or formed axially opposite the sealing ring (9) on the axially front side of the toothed region (71). [10] Geared turbofan engine according to claim 9, characterized by that the further sealing element is formed by a further sealing ring (33) which is formed integrally with the sun gear (3) or fastened thereto, wherein the further sealing ring (33) is arranged and designed such that it forms a gap (56) to the turbine shaft (2), through which oil can be introduced into the toothing area (71) in the axial direction. [11] Geared turbofan engine according to one of the preceding claims, characterized by that a means (27, 97) cooperating with the sealing ring (9) is provided which couples the rotation of the sealing ring (9) to the rotation of the turbine shaft (2). [12] Geared turbofan engine according to claim 11, characterized bythat the means is formed by a pin (27) connected to the turbine shaft, which extends in the radial direction and which passes through a corresponding opening (98) in the sealing ring (9), or that the means is formed by an axial extension (97) of the sealing ring (9) which engages in the external spline (21) of the turbine shaft (2). [13] Geared turbofan engine according to one of the preceding claims, characterized by that the sealing ring is made of steel, polytetrafluoroethylene (PTFE) or polyamide-imide (PAI). [14] Geared turbofan engine according to one of the preceding claims, characterized bythat the sun gear (3) has an axially rear, radially extending end face (34) and forms a chamfer (35) radially on the inside of the axially rear end face (34), which is aligned and dimensioned such that when the sun gear (3) is pushed onto the turbine shaft (2) for assembly purposes, the sealing ring (9) comes to rest on the chamfer (35) of the sun gear (3), the sealing ring (9) is compressed by the shape of the chamfer (35) upon further axial displacement of the sun gear (3) in the radial direction and finally rests under tension with its radially outer circumferential surface on the inner circumferential surface (32) of the sun gear (3). [15] Geared turbofan engine according to one of the preceding claims, characterized by that the geared turbofan engine further comprises: - a plurality of planetary gears (4) driven by the sun gear (3), - a ring gear (5) with which the plurality of planetary gears (4) are in engagement, and - a plurality of planetary pins (6), wherein each planetary pin (6) is arranged in a planetary gear (4) and the planetary pin (6) and the planetary gear (4) form a lubricated bearing (65), wherein the planetary pins (6) are coupled to a torque carrier (70) and the torque carrier (70) is coupled to the fan shaft (14). [16] Spline shaft arrangement comprising - a drive shaft (2) having an external spline (21), - an output element (3) having an internal spline (31) and driven by the drive shaft (2), wherein - the external spline (21) and the internal spline (31) form a spline connection (7) between the drive shaft (2) and the output element (3), - the splined shaft connection (7) has a toothed area (71) which is lubricated with oil, and - sealing means (9, 33) are provided which seal the oil in the toothing area (71) against axial leakage, wherein the sealing means (9, 33) have a sealing ring (9), characterized by , that - the sealing ring (9) is elastic, variable in its diameter and tensioned outwards and the sealing ring (9) rests with its radially outer circumferential surface on an inner circumferential surface (32) of the output element (3) and - the sealing ring (9) and / or the groove (22) are designed such that oil can be introduced into the toothing area (71) through a radial gap (55) under the sealing ring (9). [17] Spline shaft arrangement according to claim 16, characterized bythat the external spline (21) of the drive shaft (2) extends axially beyond the toothing region (71) and forms an extension region (212) of the external spline (21) axially adjacent to the toothing region (71), the sealing ring (9) is arranged in a groove (22) running in the circumferential direction of the drive shaft (2) and the groove (22) is formed in the extension region (212) in the external spline (21) of the drive shaft (2). [18] Spline shaft arrangement according to claim 16 or 17, characterized by that the sealing ring (9) has two ends (93, 94) which are adjacent to one another and overlap one another, the degree of overlap determining the diameter of the sealing ring (9).

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