Transmission drive train with tilt compensation
The gear drive train with an eccentric offset between bearing components minimizes gear tooth tilting, improving load-bearing capacity and safety by ensuring uniform loading, addressing the issue of gearbox weight-induced tilting in wind turbines.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FLENDER GMBH
- Filing Date
- 2025-12-15
- Publication Date
- 2026-06-25
AI Technical Summary
Wind turbines experience gear tooth tilting due to the weight of the gearbox-generator unit, leading to uneven loading and reduced torque capacity, particularly in designs with single-sided bearings or high bearing compliance.
A gear drive train design with an eccentric offset between the housing-side bearing seat and the bearing raceway, compensating for the tilting moment by rotating the planetary gear carrier bearings, ensuring uniform loading and preventing angular misalignment.
The solution significantly reduces gear tooth tilting, enhancing load-bearing capacity and safety by maintaining uniform loading, applicable to both new and retrofitted gearboxes.
Smart Images
Figure EP2025087110_25062026_PF_FP_ABST
Abstract
Description
[0001] FLENDER GMBH Düsseldorf, December 15, 2025
[0002] Our reference number: FD 45749 - 2024P04726WO
[0003] Flender GmbH
[0004] Alfred-Flender-Str. 77, 46395 Bocholt, Germany
[0005] Gear drive train with tilt compensation
[0006] Description
[0007] The invention relates to a gear drive train with a drive train axis AD for a wind turbine for torque transmission in one direction M, comprising a gear housing, at least one first planetary stage rotatable about the drive train axis AD or at least one first planetary stage and a subsequent spur gear stage, wherein a ring gear of the at least first planetary stage is designed as a housing component of the gear housing and the first planetary stage has a planet gear carrier with a first central axis AMI with planet gears received therein, wherein the planet gear carrier is rotatably mounted relative to the gear housing with a first and second bearing viewed in one direction M.
[0008] Wind turbines can be equipped with so-called three-point mounting systems. In this system, the force and tilting moment resulting from the gearbox mass are supported by a torque arm and the main shaft bearing. For this purpose, the planetary gear carrier and the main shaft are rigidly coupled. The generator, connected on the output side, has a separate support on the machine frame. Its mass is not supported by the multi-blade rotor or main shaft bearings, nor by the gearbox.
[0009] For wind turbines, however, a mounting system can also be used in which a main shaft is supported at two points and a torque arm is provided, whereby the torque arm only exhibits high stiffness in the direction of the reaction torque it is supporting and does not absorb purely radial forces. Furthermore, the generator is directly flanged to the gearbox output and does not have additional support on the machine frame. The planetary gear carrier is rigidly connected to the main shaft. In this design, the entire weight of the gearbox-generator unit, with the exception of the input-side planetary gear carrier, rests on the planetary gear carrier's bearing.
[0010] The weight of the gearbox-generator unit – also known as the core gearbox – and bearing compliance cause deformation in the bearings, which can lead to unfavorable tilting of the gear teeth. This effect is particularly pronounced with a single-sided bearing or significant deflection due to the high weight of the core gearbox or high bearing compliance. The tilting of the gear teeth results in uneven and unfavorable loading and must be considered in the design, leading to heavier designs or gearboxes with lower torque carrying capacity. There is a constant need to minimize, and ideally eliminate, this tilting of the gear teeth. In this context, EP 1 788 281 A1 should be mentioned, where tilting is caused by an eccentric bearing seat in which an unmodified bearing is fitted.
[0011] The purpose of the invention is to demonstrate measures that at least minimize the tilting in the gearing.
[0012] The problem is solved by a gear drive train with the features of claim 1. Preferred embodiments are specified in the dependent claims and the following description, each of which, individually or in combination, can represent an aspect of the invention. When a feature is presented in combination with another feature, this serves only to simplify the presentation of the invention and is in no way intended to imply that this feature cannot also be a further development of the invention without the other feature. One embodiment relates to a gear drive train with a drive train axis AD for a wind turbine for torque transmission in one direction M, comprising a gear housing, at least one first planetary stage rotatable about the drive train axis AD, or at least one first planetary stage and a subsequent gear stage.wherein a ring gear of at least the first planetary stage is designed as a housing component of the gearbox housing and the first planetary stage has a planet carrier with a first central axis AMI with planet gears received therein, wherein the planet carrier is rotatably mounted relative to the gearbox housing with a first and second bearing viewed in the direction M, wherein a housing-side bearing seat of at least one of the two bearings arranged about the drivetrain axis AD, which for the sake of simplicity is assumed to be horizontal, and a bearing raceway of a bearing ring of the at least one bearing receiving in the bearing seat having an eccentric offset to each other in a direction of the weight force FRG acting on the gearbox drivetrain.
[0013] For the purposes of this analysis, a distinction must be made between an unloaded and a loaded state. A state in which the force of gravity does not act on the transmission drive train or on any of its components can also be described as an unloaded or unloaded state. In such a state, the transmission drive train is not subjected to its own weight, so there are no deformations due to material compliance. Any play between moving parts is not exploited to one side, but rather remains within the range of its tolerance. This state, in which the force of gravity is not effective, can initially be described as a virtual state, for which the design is planned using a suitable calculation program during the design phase.
[0014] In addition to the drivetrain axis AD, a first central axis AMI can be defined for the first planetary stage, and a second central axis AM2 for the gearbox housing, including any further planetary stages. For the described unloaded state, it can be specifically provided that the second central axis AM2 is inclined vertically upwards from an intersection point with the first central axis AMI in the direction of at least the second planetary stage. In the described unloaded state, the central axis AM2 of the gearbox housing is arranged at an angle avK to the drivetrain axis AD, so that a tilting occurs between the gear teeth. This tilting in the unloaded state, however, is a virtual state, since the gearbox drivetrain is not in operation.When the unloaded state is released, the tilting moment resulting from the weight of the gearbox housing and the other planetary stages takes effect, causing the gearbox housing to compress and reducing or even eliminating the tilting in the gearing.
[0015] The proposed gear drive train avoids or at least significantly reduces the negative effect of gear tilt, particularly in the first planetary stage, resulting in a considerably improved load-bearing capacity of the gears. Uneven loading within the first planetary stage's gearing—especially between the ring gear and the planet gears—is prevented. The initial, or design-integrated, eccentric offset between the housing-side bearing seat and the bearing raceway of the seated bearing ring ensures that the planetary axes exhibit no angular misalignment with the ring gear during operation, thus guaranteeing uniform loading of the first planetary stage's gearing. The use of planetary gear carrier bearings manufactured according to the invention alone compensates for the negative effect of gear tilt.Another advantage is that gearboxes developed without the described tilt compensation could also be retrofitted. This increases the safety and load-bearing capacity of the first planetary stage.
[0016] In a preferred embodiment of the transmission drive train, the eccentric offset V r The bearing raceway of the housing-side bearing ring of the first bearing is oriented opposite to the direction of the weight force FRG acting on the transmission drive train, relative to the drivetrain axis. Consequently, the rotating bearing ring of the first bearing is displaced, and thus the supported planetary gear carrier is tilted relative to its initial state.
[0017] In a further preferred embodiment of the transmission drive train, the eccentric offset V rThe bearing raceway of the housing-side bearing ring of the second bearing is oriented in the direction of the weight force FRG acting on the transmission drive train, relative to the drivetrain axis AD. Consequently, the rotating bearing ring of the second bearing is displaced, and thus the supported planetary gear carrier is tilted relative to its initial state.
[0018] Thus, it is possible to provide that the bearing raceway of the first bearing, which is the rotor-side bearing, and / or the bearing raceway of the second bearing, which is the generator-side bearing, are displaced in opposite directions. In a specific embodiment, it is possible that the first and second bearings are each designed as rolling bearings. In one possible embodiment with regard to the bearing arrangement, the first and second bearings can be arranged on opposite sides of the planet carrier when viewed in the torque direction M. In an alternative embodiment with regard to the bearing arrangement, the first and second bearings can be designed as double tapered roller bearings in an O-arrangement or X-arrangement, viewed in the direction M, on the input or output side of the planet carrier.
[0019] In a further preferred embodiment, it may be provided that a central axis AL of the bearing raceway of the housing-side bearing ring of the first and / or the second bearing is additionally angled relative to the drive train axis AD.
[0020] In a further preferred embodiment of the gear drive train, an outer bearing ring of the first bearing is held in the housing-side bearing seat, and an inner bearing ring or an outer bearing ring of the second bearing is held in the housing-side bearing seat. In a further embodiment of the gear drive train, an electric machine connected to the gear housing may be arranged downstream of at least one planetary stage.
[0021] The task is further solved by a wind turbine with a rotor shaft driven by a rotor flange with a multi-blade rotor, wherein the rotor shaft drives a geared drive train designed as described.
[0022] The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show:
[0023] Fig. 1: a schematic representation of a drive train of a wind turbine,
[0024] Fig. 2: schematic and partial representation of a gear drive train,
[0025] Fig. 3: a detailed view of the transmission drive train according to Fig. 2 with radially offset planetary gear carrier bearings,
[0026] Fig. 4, 5: an embodiment of a gear drive train for compensating for an angular tilting and
[0027] Fig. 6: a detailed view of the first bearing of the first planetary gear carrier.
[0028] Figure 1 shows a schematic representation, not to scale, of a wind turbine 100 in one possible configuration. A side view with a partial sectional view is shown. The wind turbine 100 is positioned opposite a tower (not shown) at an inclination of typically approximately 5°. The present description is independent of this inclination and refers to the xyz coordinate system shown in Figure 1. A drive train axis AD of the wind turbine 100 runs parallel to the x-axis of the xyz coordinate system. A key element of the wind turbine 100 is a drive train 102, which in this case can structurally comprise a rotor flange 104 with a multi-blade rotor 106, a rotor bearing 108, a gearbox component 110, and a generator 112. At least the rotor bearing 108 and the generator 112 are supported on a ground via a machine carrier 114 and a tower (not shown).The rotor bearing 108 comprises a rotor shaft 118, which is rotatably mounted about the drivetrain axis AD relative to a rotor bearing housing 120 of the rotor bearing 108, for example, via an angled tapered roller bearing. The drivetrain axis AD defines an axial direction. M denotes a torque direction in a standard operating condition.
[0029] The rotor flange 104 is mounted at one end of the rotor shaft 118, and the multi-blade rotor 106 is mounted to the flange. The other end of the rotor shaft 118 is connected to a gear unit 110 to transmit the drive torque applied by the multi-blade rotor 106. The gear unit 110 is a planetary gear unit with one or more planetary stages. The gear unit 110 is connected to the generator 112. The rotor shaft 118 is connected to the gear unit 110 via a flange 126. A reaction torque resulting from the torque transmission of the gear unit 110—and also of the flanged generator 112—is supported against the machine carrier 114 by a torque arm 116. In a first embodiment, the torque arm 116—as shown in Figure 1—can connect the gear unit 110 directly to the machine carrier 114.The machine carrier 114, the rotor bearing 108 with rotor shaft 118, the torque support 116 and the gearbox component 110 can be referred to as gearbox drive train 10.
[0030] Figure 2 schematically and partially shows a geared drive train 10 for a wind turbine 100, driven about the drive train axis AD, as shown, for example, in Figure 1. A gearbox housing 12 is provided, in which, in this case, a first, a second, and a third planetary gear stage 20, 22, and 40, and a spur gear stage 44 can be accommodated. A generator 112 can also be flanged to the gearbox housing 12. The second and third planetary gear stages 22 and 40 and the spur gear stage 44 are shown here only by their reference numerals as placeholders. A ring gear 14 of the first planetary gear stage 20 is designed as a housing component of the gearbox housing 12. The first planetary gear stage 20 has a planet gear carrier 16 with planet gears 18 accommodated therein. A sun gear of the planetary gear stage 20 is not shown here.The planet carrier 16 is rotatably mounted relative to the gearbox housing 12 on a first axial side by a first bearing 26i and on a second axial side by a second bearing 262. The gearbox housing 12 has corresponding bearing seats 28 and 34 on its side for this purpose. The designations "first" and "second axial side" initially refer to the drive shaft AD. Furthermore, for the purposes of this discussion, it is defined that the first axial side is the side facing the multi-blade rotor 106 – see Figure 1 – and the second axial side is the side facing the generator 112.
[0031] The ring gear 14 of the first planetary stage 20, the second and third planetary stages 22, 40, and the optional generator 112 are hereinafter also designated with the reference numeral 24 and referred to as the core gearbox. The gearbox housing 12 is considered part of the core gearbox 24. For the planet carrier 16 of the first planetary stage 20 and the core gearbox 24, respective component-specific center axes AMI and AM2 can be defined. Due to the tilting moment MK resulting from the weight force FRG of the core gearbox 24, and as a result of any bearing clearance and compliance of the bearings 26i, 262 and the housing structure or bearing seats, the core gearbox 24 experiences an angular tilting. This angular tilting is shown in Figure 2 and can be described as a loaded state, in contrast to an unloaded state in which no weight force FRG is acting and which is described with reference to Figure 4.The central axis AM2 of the gearbox 24 is therefore tilted downwards by an angle -avK relative to the central axis AMI of the first planet carrier 16. The tilted central axis AM2 of the gearbox 24 is inclined at the angle -avK, where the magnitude of the angle avK describes the position of the central axis AM2 of the gearbox 24 relative to the central axis AMI of the first planet carrier 16. The negative sign of the angle avK describes the orientation of the central axis AM2 relative to the central axis AMI; namely, starting from an intersection point between the central axis AMI and the central axis AM2, the central axis AM2 is inclined vertically downwards in the direction of the gearbox 24.
[0032] The angular tilting -avK leads to a tilting of the gear teeth in the planetary stage 20, in particular between ring gear 14 and planet gears 18 of the planet carrier 16. For the consideration of the angular tilting due to the weight force FRG of the core gearbox 24 and the resulting tilting moment MK, a fixed or unchanged position of the planet carrier 16 is assumed.
[0033] Figures 3, 4, and 5 show an embodiment of a geared drive train 10 for compensating the angular tilting caused by the weight force FRG of the gearbox housing 24. Figure 3 shows a comparison of a conventional bearing configuration and a bearing configuration for compensating the angular tilting caused by the weight force FRG of the gearbox housing 24 for the left, i.e., rotor-side, bearing 26i. In each case, the bearing 26i is seated in a bearing seat 28 of the gearbox housing 12. The bearing seat 28 is arranged concentrically around the drive train axis AD and has a bore radius designated RB. The bearing 26i is designed as a rolling bearing and has an outer bearing ring 30, an inner bearing ring 32, and rolling elements 50 running between them. The bearing ring 30 has a bearing raceway 48 with a central axis AL with a raceway radius designated as RL.In the bearing configuration for compensating the angular tilting, the housing-side bearing ring 30 of the bearing 261 is now modified in such a way that an eccentric offset V. r between the central axis AL of the bearing raceway 48 and the drivetrain axis AD of the bearing seat 28. This eccentric offset V r Figure 3 illustrates the bore radius RB, the raceway radius RL, and the drivetrain axis AD and central axis AL, which are not concentric but spaced apart and parallel to each other. In Figure 3, the gearbox housing 12 and the planet carrier 16 are still shown in a coaxial position relative to each other. Figure 4 shows the unloaded state, in which the gearbox housing 24 is not subjected to its own weight FRG, so that there are no deformations due to material compliance. Figure 4 also shows the eccentric offset V. rbetween the central axis AL of the bearing raceway 48 and the drivetrain axis AD of the bearing seat 28, as described in Figure 3. The planet carrier 16 has an unchanged horizontal position in Figures 3 and 4, so that in Figure 4 the gearbox housing 12 and the main gearbox 24 are pivoted vertically upwards to accommodate the eccentric offset V r between the central axis AL of the bearing raceway 48 and the drivetrain axis AD of the bearing seat 28. The central axis AM2 of the core gearbox 24 is therefore inclined upwards by an angle +avK relative to the central axis AMI of the first planet carrier 16.
[0034] Figure 5 shows the loaded state in which the gearbox 24 experiences an angular downward tilting due to the tilting moment MK resulting from the weight force FRG. This is due to the eccentric offset V described in Figures 3 and 4. rBetween the central axis AL of the bearing race 48 and the drivetrain axis AD of the bearing seat 28, the central axis AM2 of the core gearbox 24 now lies coaxially with the central axis AMI of the first planet carrier 16 and coaxially with the drivetrain axis AD. This coaxial orientation of the two central axes AMI and AM2 to each other ensures that there is no tilting of the gear teeth in the planetary stage 20, in particular between the ring gear 14 and the planet carrier 16.
[0035] Figure 6 shows a detailed view of the first bearing 26i. It can be seen that a central axis AL of a raceway 48 of the housing-side bearing ring 30 of the first bearing 261 is angled relative to the drivetrain axis AD. Reference sign list
[0036] 10 Transmission drivetrain
[0037] 12 Gearbox housings
[0038] 14 Ring gear
[0039] 16 PI anetenradträger
[0040] 18 planetary gears
[0041] 20th planetary stage
[0042] 22nd planetary stage
[0043] 24 trunk gearboxes
[0044] 26 warehouses
[0045] 28 bearing seat
[0046] 30 bearing ring
[0047] 32 inner bearing ring
[0048] 34 bearing seat
[0049] 40th planetary stage
[0050] 44th stage of the twang wheel
[0051] 48 Warehouse career
[0052] 50 rolling elements
[0053] 100 wind turbines
[0054] 102 Drive string
[0055] 104 Rotor flange
[0056] 106 multi-blade rotor
[0057] 108 Rotor bearing
[0058] 110 Gearbox component
[0059] 112 Generator
[0060] 114 machine carriers
[0061] 116 Torque support
[0062] 118 Rotor shaft
[0063] 120 Rotor bearing housing 126 Flange
Claims
P a t e n t a n s p r ü c h e 1. Gear drive train (10) with a drive train axle (AD) for a wind turbine (100) for torque transmission in one direction (M), comprising a gearbox housing (12), at least one first planetary stage (20) rotatable about the drive train axle (AD), or at least one first planetary stage (20) and a subsequent spur gear stage (44), wherein a ring gear (14) of the at least first planetary stage (20) is designed as a housing component of the gearbox housing (12), and the first planetary stage (20) has a planet carrier (16) with a first central axle (AMI) with planet gears (18) received therein, wherein the planet carrier (16) is rotatably mounted relative to the gearbox housing (12) with a first and second bearing (26i, 262) viewed in the direction (M), wherein a housing-side bearing seat (28, 34) arranged about the drive train axle (AD), which is assumed to be horizontal, supports at least one of the two bearings (26i, 262).262) and a bearing raceway (48) extending about a central axis (AL) of a bearing ring (30) received in the bearing seat (28) of at least one bearing (26i, 262) with an eccentric offset (V, r ) in one direction of the weight force FRG acting on the transmission drive train (10) towards each other.
2. Gear drive train (10) according to claim 1, characterized in that the eccentric offset (+V r ) the bearing raceway (48) of the first bearing (26i) is directed opposite to the direction of the weight force (FRG) acting on the transmission drive train (10) with respect to the drive train axis (AD).
3. Gear drive train (10) according to claim 1 or 2, characterized in that the eccentric offset (+Vr) of the bearing raceway (48) of the second bearing (262) with respect to the drive train axis (AD) is directed in the direction of the weight force (FRG) acting on the gear drive train (10).
4. Gear drive train (10) according to one of claims 1 to 3, characterized in that the first and the second bearing (26i, 262) are each designed as a rolling bearing or a sliding bearing.
5. Gear drive train (10) according to one of claims 1 to 4, characterized in that the first and the second bearing (26i, 262) is designed as a double tapered roller bearing in an O-arrangement or X-arrangement in the direction (M) viewed on the input or output side of the planet carrier (16), or with another bearing design.
6. Gear drive train (10) according to one of claims 1 to 4, characterized in that the first and the second bearing (26i, 262) are arranged on opposite sides of the planet carrier (16) when viewed in the direction (M).
7. Gear drive train (10) according to one of claims 1 to 6, characterized in that a bearing outer ring (30) of the first bearing (26i) is held in the housing-side bearing seat (28) and a bearing inner ring (32) or a bearing outer ring of the second bearing (262) is held in the housing-side bearing seat (34).
8. Gear drive train (10) according to one of claims 1 to 7, characterized in that a central axis (AL) of the bearing raceway (48) of the housing-side bearing ring (30) of the first and / or the second bearing (26i, 262) is angled relative to the drive train axis (AD).
9. Gear drive train (10) according to one of claims 1 to 8, characterized in that an electric machine (112) connected to the gear housing (12) is arranged downstream of the at least one planetary stage (20). - 15 - 10. Wind turbine (100) comprising a rotor shaft (118) driven by a rotor flange (104) with a multi-blade rotor (106), characterized in that the rotor shaft (118) drives a gear drive train (10) designed according to claim 9.