Wind turbine powertrain

Abstract

The invention describes a wind turbine powertrain (1) comprising: a planetary gearbox (12) for converting rotation of a low speed shaft (10) into rotation of a high speed gearbox output shaft (122); a generator (14) mounted around an annular sleeve (124), the annular sleeve (124) extending axially outward from the gearbox housing (12H) and surrounding the gearbox output shaft (122); a bearing assembly (16) disposed between the generator (14) and the gearbox (12), the bearing assembly (16) comprising a swivel bearing portion (16R) and a stationary bearing portion (16S); and a torsional vibration damper (13) arranged between the two rotating components (122, 122A, 122B, 14R, 16R) of the power train (1), the torsional vibration damper (13) comprising a plurality of damping elements (13E). The wind turbine powertrain is characterized in that the torsional vibration damper (13) is dimensioned to facilitate internal access from the generator (14). The invention also describes a method of implementing a maintenance procedure for such a wind turbine powertrain (1).

Description

Background Technology

[0001] The power transmission system of a wind turbine may include a low-speed shaft rotated by an aerodynamic rotor, a gearbox with a high-speed output shaft, and a generator connected to the high-speed shaft. In known types of medium-speed power systems, the gearbox is a multi-stage planetary gearbox, and the generator is coaxially mounted to the gearbox. In this implementation, the low-speed shaft, the planetary gearbox sun shaft, and the generator rotor substantially share a common axis of rotation.

[0002] Instead of fixing the generator housing to the base plate or other fixed structures, the generator housing is cantilevered to the gearbox housing. This cantilevered powertrain design has various advantageous features, such as the bearing assembly, which primarily supports the gearbox output shaft, can also be used to center and support the generator rotor. This bearing assembly, or "gearbox-generator bearing," which may include, for example, a pair of tapered roller bearings, is typically implemented in the form of a housing that can be treated as a single unit and pulled out to the rear of the generator. Furthermore, the gearbox-generator bearing can be lubricated from the gearbox lubrication system, thus avoiding the need for a dedicated lubrication system for the generator.

[0003] However, tonal noise can be a problem in powertrains with this type of configuration. Tonal noise can arise when structurally propagated vibrations caused by gear excitation coincide with the intrinsic modes of other structural components of the powertrain or wind turbine. Tonal noise can also originate from small, but unavoidable, torsional oscillations in torque transfer components (e.g., the gearbox sun shaft), which can cause vibrations to propagate through the gearbox / generator connection. Structurally propagated vibrations originating from the generator or gearbox can be transferred to the main shaft housing and from there to the base plate and tower, or to the main shaft, hub, and rotor blades. This structurally propagated vibration is converted into audible noise when components of the wind turbine (e.g., rotor blades, tower, etc.) act as a type of amplifier or loudspeaker. While the occurrence of this tonal noise is not relevant to offshore facilities, it can be a problem for onshore facilities near residential areas, as wind turbine noise may be required to not exceed the acceptable thresholds specified in applicable noise regulations.

[0004] Therefore, for the use of cantilevered powertrain configurations in onshore facilities, it may be necessary to take corrective measures to counteract tonal noise so that the wind turbine can comply with applicable noise regulations. One approach is to mitigate, to some extent, the transfer of structurally propagated noise from the powertrain to the amplified components of the wind turbine by incorporating suitable dampers at strategic locations (e.g., between the powertrain housing and the base plate). However, structural noise is not completely eliminated, meaning that some acoustic wind turbine noise can still be perceived.

[0005] In an alternative approach, gearbox-generated noise propagating structurally can be suppressed by installing a large torsional damper between the sun gear of the final gearbox stage and the generator input shaft. Depending on its design, this torsional damper may also require lubrication and therefore must be connected to an oil supply and drainage system. The purpose of this type of damper is to ensure a vibration-free connection between the gearbox and the generator. While effective, this method suffers from the difficulty of accessing and maintaining the large damper, and because its lifespan may be much shorter than that of the wind turbine, maintenance procedures will be required at certain stages. Accessing the torsional damper necessitates the complete removal of the generator and the gearbox / generator bearings. These procedures are time-consuming, difficult, and can result in significant downtime. Therefore, this prior art noise reduction method is associated with unfavorable high costs.

[0006] Therefore, the object of the present invention is to provide a more economical method for reducing structurally transmitted noise in this type of powertrain.

[0007] This objective is achieved by the stated wind turbine powertrain and by the stated methods of maintaining the powertrain. Summary of the Invention

[0008] According to the present invention, a wind turbine powertrain includes: a planetary gearbox for converting rotation of a low-speed shaft into rotation of a high-speed gearbox output shaft; a generator mounted around an annular sleeve extending axially outward from the gearbox housing in the downwind direction; a bearing assembly disposed between the generator and the gearbox, the bearing assembly including a rotating bearing portion and a stationary rotating bearing portion; and a torsional vibration damper disposed between two rotating components of the powertrain, the torsional vibration damper including a plurality of damping elements. The powertrain of the present invention is characterized in that the torsional vibration damper is sized and arranged to facilitate access from within the generator. In other words, to obtain access to the torsional damper, access to the interior of the generator is sufficient, and if necessary, the torsional damper can then be removed from the generator. Similarly, after obtaining access to the torsional damper from within the generator, field maintenance procedures can be performed on the damper.

[0009] The powertrain of the present invention may include one or more torsional dampers arranged at various locations between the output shaft and the interior of the generator. Each torsional damper is accessible from the interior of the generator due to its advantageous size and / or its advantageous placement. Even when arranged around the gearbox output shaft, the torsional dampers of the powertrain of the present invention can be accessed from the interior of the generator, for example, for replacement or maintenance procedures.

[0010] In the aforementioned cantilevered powertrain configuration, where the generator is supported by the gearbox and not rests on a base plate, a torsional damper is used to enhance the transmission of vibrations between the gearbox and the generator. By incorporating the torsional damper at the connection between the gearbox and the generator, acoustic noise originating from gearbox vibrations and / or generator vibrations propagated through the structure is advantageously reduced or even eliminated.

[0011] Another advantage of the powertrain configuration of this invention is that it eliminates the need to remove the generator or gearbox / generator bearings from the powertrain to access the torsional damper. Instead, according to the invention, a method for performing a maintenance procedure on the powertrain includes the following steps: removing the generator's rear cover; removing any generator components on the downwind side of the torsional damper, if necessary; releasing the fasteners of the torsional damper; and removing the torsional damper through the rear of the generator. A replacement torsional damper can then be installed, and the generator reassembled in reverse order. This procedure can be performed relatively easily and in a favorable short time. The method of this invention does not involve the type of heavy equipment required to lift or move the generator. This is a significant advantage because the generator in such a wind turbine powertrain can have a mass of approximately 4,000-8,000 kg and requires specialized lifting equipment. Therefore, the ability to access the torsional damper without removing the generator is a highly valuable design feature.

[0012] Particularly advantageous embodiments and features of the invention are given by the dependent claims, as disclosed in the following description. Features from different claim classes may be combined as appropriate to give other embodiments not described herein.

[0013] In the following text, without limiting the invention in any way, it may be assumed that the powertrain is intended for use in indirect-drive wind turbines, particularly for onshore wind turbine installations. Gearbox / generator bearings may be referred to herein simply as “bearings,” “bearing assemblies,” or “bearing housings.”

[0014] In the following description, it is assumed that the generator is mounted around an annular sleeve extending axially from the gearbox housing in the downwind direction. This annular sleeve is part of the gearbox housing and serves to provide support for the gearbox / generator bearings. The gearbox / generator bearing housing may be arranged inside this annular sleeve. Alternatively, the gearbox / generator bearing housing may be arranged around the outside of the annular sleeve.

[0015] Since the low-speed shaft and gearbox sun shaft can be hollow, coaxial alignment of the powertrain components can be achieved by arranging hollow tubes within the internal spaces of the low-speed shaft, gearbox, and generator, and using these hollow tubes as cable conduits for electrical cables (e.g., cables from the wind turbine controller to the pitch system of the rotor blades) leading to the hub. These cable conduits can extend from inside the gearbox output shaft toward the rear of the powertrain and through the generator.

[0016] The terms “torsional vibration damper” and “torsional damper” should be understood as synonyms and can be used interchangeably herein. They should also be understood as referring to a damper that does not require lubrication, i.e., the torsional damper of the power transmission system of the present invention does not require a connection between an oil supply and drainage device.

[0017] The torsional damper can be implemented in any suitable manner. In a preferred embodiment of the invention, the torsional vibration damper has an overall annular shape with a central circular opening, comprising: an inner annular arrangement of threaded axial bores for connection to a first rotating component of the powertrain; and an outer annular arrangement of threaded axial bores for connection to a second rotating component of the powertrain. The bores are formed to receive axial fasteners that will be inserted into the relevant rotating powertrain component in the upwind direction (i.e., from inside the generator).

[0018] In a particularly simple implementation, the torsional vibration damper comprises a single annular damping element arranged between an inner annular bore arrangement and an outer annular bore arrangement.

[0019] In another preferred embodiment of the invention, the torsional vibration damper includes a plurality of cavities and a damping element disposed in each cavity. The plurality of cavities are formed in a region between an inner annular bore arrangement and an outer annular bore arrangement.

[0020] Regardless of how a torsional damper is constructed, its (one or more) damping elements absorb the torsional deflection of the rotating components of the power transmission system; that is, the torsional damper imparts a certain degree of elasticity to the connection it forms between two rotating components.

[0021] The desired damping characteristics can be achieved in various ways. For example, the damping characteristics can be determined by the material used to make the damping element and the shape of the damping element. In the case of a torsional damper with a single annular damping element, the damping element can be made of rubber or a similar elastomer and can be clamped or otherwise contained between the inner annular bore arrangement and the outer annular bore arrangement.

[0022] In the case of a torsional damper with multiple damping elements, these damping elements can each be made of a suitable elastomer and shaped to fit tightly into the cavity. For example, the damping element can be provided in the form of a cylinder of hard rubber or a similar material, and positioned in the cavity such that its circular end face abuts against the opposing face of the cavity. During operation of the powertrain, the kinetic energy generated by vibrations produced by the structure is converted into heat through the deformation of the elastic material of the damper element.

[0023] In another preferred embodiment of the invention, the damping element is preloaded, i.e., the length of the damping element exceeds the length of the cavity, such that the damping element must be compressed before being inserted into the cavity.

[0024] In another preferred embodiment of the invention, the damping element comprises two or more parts. For example, the damping element may include one or more of the following: a spring; a friction element; or a piston assembly.

[0025] Regardless of the design of the torsional damper, the heat generated by the conversion of kinetic energy can be dissipated into the surrounding environment.

[0026] There are various possible ways to place this type of torsional damper at the connection between the gearbox and the generator.

[0027] For example, the torsional damper can be placed very close to the output stage of the gearbox. It may be preferable that the final stage of the gearbox includes a helical gear on the output shaft that generates axial forces.

[0028] To facilitate this configuration, the gearbox output shaft can be implemented in two sections, with a first section terminating near the output stage and a second section extending into the annular sleeve and generator. A torsional damper is connected between these two sections, thereby transferring axially directed forces between the first section of the shaft and the rotating bearing portion. During wind turbine operation, vibrations are not transmitted between the first and second output shaft sections. For use in this configuration, a damper design unaffected by oil-lubricated environments is preferred.

[0029] The advantage of the above embodiment is that the torsional damper provides angular flexibility to the gearbox output shaft, thus allowing the sun pinion of the final gearbox stage to be optimally aligned with the planetary gears. This eliminates the need for a splined coupling, which would otherwise be required to achieve proper angular alignment of the gearbox output shaft. In this embodiment, the torsional damper also absorbs the axial load transferred from the gearbox output shaft, thus avoiding the need for a separate axial load bearing.

[0030] In any power transmission configuration in which the gearbox includes a helical gear in the last stage and in which a torsional damper is connected to the gearbox output shaft, the torsional damper effectively dampens the axial vibration of the gearbox output shaft and prevents it from being transmitted to the bearing housing.

[0031] Alternatively or additionally, the torsional damper can be positioned between the non-drive end of the gearbox output shaft and the bearing. In this configuration, the torsional damper can be connected to the upwind end of the bearing, or, if a longer gearbox output shaft is desired, to the downwind end. In the configuration where the torsional damper is connected to the downwind end of the bearing, the bearing can be arranged within or around an annular sleeve. In each case, as explained above, during wind turbine operation, neither axial nor radial vibrations are transmitted between the rotating components on either side of the torsional damper. However, the torsional damper does not affect the transfer of axial and radial forces to the bearing and therefore does not impair its function. For example, in the case where the helical gear in the last stage of the gearbox applies an axial force to the gearbox output shaft, this axial force is transmitted to the bearing housing by the torsional damper. This configuration may be preferable in powertrains employing long gearbox output shafts because the torsional damper provides additional elasticity to the output shaft and improves vibration behavior.

[0032] In another preferred embodiment of the invention, the torsional damper includes an annular seal arranged to prevent contaminants from entering the generator. For example, the annular seal may be arranged around the inner circumference of the damper (i.e., around its central opening) to prevent contaminants such as lubricating oil from the gearbox and / or spline connections and / or bearings from being transmitted into the generator's interior. Alternatively or additionally, the torsional damper, positioned around the downwind end of the cable conduit, may be equipped with a support bearing around its annular orifice to support the cable conduit.

[0033] Alternatively or additionally, the torsional damper can be arranged between the gearbox / generator bearing and the gearbox output shaft. For example, the bearing can be arranged within an annular sleeve, and the torsional damper connects the gearbox output shaft and the downwind end of the bearing. Alternatively, the bearing can be arranged around the annular sleeve, and the torsional damper connects the gearbox output shaft and the downwind end of the bearing. Likewise, in any variation of this configuration, the torsional damper dampens axial and / or radial vibrations in the gearbox output shaft section and prevents their transmission to the bearing (and vice versa). This configuration may be preferable if the damper mechanism functions optimally in a dry and oil-free environment.

[0034] In another possible configuration, the gearbox / generator bearings can be arranged around an annular sleeve, and a torsional damper can be arranged between the bearings and the generator rotor. In this embodiment, the torsional damper acts as a rotor support structure. The connection between the rotating bearing section and the torsional damper can be configured such that the bearing housing is removed first to obtain access to the damper, or the damper is removed first to obtain access to the bearing housing. In any variation of this configuration, the inner diameter of the torsional damper is relatively large to match the outer diameter of the bearing housing. In this configuration, the torsional damper is preferably configured such that its damping element(s) provides electrical isolation between the generator rotor and the bearing, thus preventing stray currents from being transmitted to the gearbox / generator bearings. Similarly, axial and radial vibrations in the gearbox output shaft section are allowed to be transmitted to the bearings, but are prevented from being transmitted to the generator rotor. Likewise, vibrations originating from the generator are allowed to be transmitted to the bearings, but are prevented from being transmitted to the gearbox. This configuration may be preferable if the desired damping characteristics can be achieved by constructing a torsional damper with a larger diameter.

[0035] Depending on the selected configuration, accessing the torsional damper may be very simple, or it may require the removal of one or more generator components. For example, if the torsional damper is connected to the downwind end of the bearing, it is essentially directly accessible and can be removed after unscrewing the inner and outer fasteners. Alternatively, maintenance may involve removing the bearing to gain access to the torsional damper. In a configuration where the torsional damper is located between the upwind end of the bearing and the generator rotor, maintenance may involve removing the rotor support sleeve to gain access to the torsional damper. In a configuration where the torsional damper is located between two sections of the generator output shaft, maintenance may involve removing the rotor support sleeve, the bearing housing, and the second output shaft section to gain access to the torsional damper. However, regardless of the selected configuration, it is not necessary to remove the generator from the gearbox to access the torsional damper. If it is necessary to disconnect the generator rotor from the bearing, the generator rotor can be locked in place, for example, using a suitable arrangement of fasteners, to prepare for maintenance procedures. Attached Figure Description

[0036] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, it should be understood that the drawings are designed for illustrative purposes only and are not intended to limit the scope of the invention.

[0037] Figure 1 - 6 illustrates various embodiments of the powertrain components of the present invention; Figure 7 - 13 illustrates an embodiment of an exemplary torsional damper for use in the powertrain of the present invention; Figure 14 A torsional damper is shown for use in a prior art powertrain.

[0038] In the accompanying drawings, similar reference numerals always refer to similar objects. Objects in the accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0039] Figure 1 Figure 6 illustrates various embodiments of the powertrain assembly 1 of the present invention, which, as explained above, is intended for installation in the nacelle of a wind turbine. Each figure shows the final stage of the planetary gear set 12 and the generator 14, as these are relevant to the present invention. It is assumed that the low-speed main shaft of the wind turbine drives the planet carrier in the first stage of the gearbox 14. The gearbox output shaft is connected to, or integrated with, the sun gear of, the final stage of the gearbox.

[0040] With the cantilevered powertrain configuration described above, the generator housing 12H is fixed to the gearbox housing 14H, so that the generator is not resting on a base plate, but is entirely supported by the gearbox 12. In the embodiment shown here, the gearbox housing 12H includes an annular sleeve 124 that extends axially into the generator 14 in the downwind direction. In other embodiments, the annular sleeve may be mounted to the gearbox housing 12H. In some embodiments, the gearbox output shaft 122 may extend a distance into this annular sleeve 124. The annular sleeve 124 may be shaped to surround or be surrounded by the bearing housing 16. The bearing housing 16 includes one or more roller bearings 160 (two are shown here) between the stationary bearing portion 16S and the rotating bearing portion 16R. The generator rotor 14R is connected to the bearing 16 by means of an annular support structure 144.

[0041] exist Figure 1 In each of the figures given in -6, a single torsional damper 13 is shown at a specific location. However, it should be understood that various embodiments can be combined as desired, such that the powertrain may employ two or more torsional dampers 13, for example, multiple dampers 13 at a specific location, and / or multiple torsional dampers 13 at different locations.

[0042] In each case, the torsional damper 13 is mounted between the two rotating power transmission sections by means of an inner annular arrangement of fasteners 131 and an outer annular arrangement of fasteners 133. All these torsional dampers 13 are arranged axially and are accessible from inside the generator 14, as shown in each figure, i.e., without removing the generator 14 from the gearbox 12 to access the torsional dampers 13. To prepare for maintenance procedures, the generator rotor 14R is secured by locking device 142, as shown in each figure.

[0043] The following describes the specific details of each of the various possible embodiments: exist Figure 1 In this configuration, the gearbox output shaft 122 is a two-piece structure, and the torsional damper 13 is mounted between the two output shaft sections 122A and 122B using a ring arrangement of fasteners 131 and 133. Therefore, the torsional damper 13 rotates together with the gearbox output shaft 122. Here, the annular sleeve 124 surrounds the bearing housing 16. The maximum diameter D of the torsional damper 13 is... 13 The inner diameter D of the annular sleeve 124 is selected to be no more than 124. 124 This allows the torsional damper 13 to be accessed via the annular sleeve 124 after the bearing housing 16 has been removed.

[0044] exist Figure 2 and Figure 3 In this configuration, the torsional damper 13 is installed between the gearbox output shaft 122 and the rotary bearing section 16R. Figure 2 In the middle, the external fastener 133 of the torsional damper attaches it to the windward end of the slewing bearing section 16R. Figure 3 In the middle, the external fastener 133 of the torsional damper attaches it to the downwind end of the swivel bearing portion 16R.

[0045] exist Figure 4 and Figure 5 In the middle, the torsional damper 13 is installed inside the generator 14, "in front" of the gearbox housing sleeve 124. Figure 4 In this configuration, the bearing housing is mounted around the sleeve 124, and the external fastener 133 of the torsional damper attaches it to the swivel bearing portion 16R. The internal fastener 131 of the torsional damper attaches it to the gearbox output shaft 122. Figure 5 In this configuration, the bearing housing is installed within the sleeve 124, and the internal fastener 131 of the torsional damper attaches it to the swivel bearing portion 16R. The external fastener 133 of the torsional damper attaches it to the generator rotor 14R.

[0046] exist Figure 6 In this configuration, the bearing housing 16 is mounted around the sleeve 124. Here, the torsional damper 13 is located between the bearing housing 16 and the rotor 14R. The internal fastener 131 of the torsional damper attaches it to the rotating bearing portion 16R, while its external fastener 133 attaches it to the generator rotor 14R.

[0047] The accompanying drawings also show a hollow tube 18 extending through the internal space of the powertrain. This hollow tube can serve as a cable conduit for electrical cables (e.g., cables from the wind turbine controller to the pitch system of the rotor blades) leading to the hub of the wind turbine. The drawings also show various annular seals and lubrication passages surrounding the rotating and stationary parts, the reasons for which are known to those skilled in the art and need not be explained here. As shown in the drawings, the annular seal 145 can be implemented as part of the torsional damper 13; for example, the seal 145 can extend around an annular opening in the damper 13. When the torsional damper 13 is removed for removal during maintenance procedures, the seal 145 is removed together with the torsional damper 13. Similarly, during powertrain assembly, the seal 145 and the damper 13 are treated as a single unit.

[0048] The accompanying drawings also show a support bearing 180 arranged to support the cable conduit 18 at its downwind end. The support bearing 180 may be supplied together with a torsional damper 13 arranged around the generator output shaft 122, such as... Figure 3 As shown in Figure 5, when the torsional damper 13 is removed for removal during maintenance procedures, the bearing 180 is removed together with the torsional damper 13. Similarly, during the assembly of the powertrain, the bearing 180 and the damper 13 are treated as a single unit.

[0049] Figure 7 - 11 illustrates an exemplary embodiment of the torsional damper 13 that can be employed in the above embodiments. In any implementation described below, the kinetic energy generated by vibrations produced by the structure is ultimately converted into heat due to the properties of the damping material and / or fluid friction and / or friction between the opposing surfaces of the various components.

[0050] exist Figure 7 - In the embodiment shown in 11, the damper 13 may include a plurality of portions 135, 136, 137, which are shaped to form a cavity 13C when the portions are assembled.

[0051] Figure 7 and Figure 8 Plan views of two embodiments are shown. Figures 9 to 12 A radial section view is shown, and Figure 13 and Figure 14 Details of possible damper element implementation schemes are shown.

[0052] like Figure 7 and Figure 8 As shown, the damper 13 has a central aperture 130, the diameter of which, depending on the situation, is similar to the diameter of the gearbox output shaft 122 (e.g., Figure 1- As shown in embodiment 5), or with a diameter large enough to be assembled around the swivel bearing portion 16R (as shown in embodiment 5). Figure 6 (As shown in the embodiment). The torsional damper 13 has an internal annular arrangement of threaded holes 132 for receiving internal fasteners 131, and an external annular arrangement of threaded holes 134 for receiving external fasteners 133. The damping effect of the torsional damper 13 is achieved by an annular arrangement of elastomers 13E arranged in the cavity 13C. Each elastomer can be made of a material with a certain degree of elasticity. The material selection and size are chosen to obtain the desired damping characteristics, which will dampen axial and / or radial vibrations in the rotating part around which the torsional damper 13 is mounted. Figure 7 and Figure 8 In this context, any damping element 13E can be preloaded by selecting its length to be slightly longer than the length of its cavity 13C. Figure 7 The cross-section is also shown to illustrate how two different damper element orientations can be achieved.

[0053] exist Figure 9 In the middle, the damping element 13E (made of Figure 8 The rectangular shape shown in the figure is essentially cylindrical and has a circular cross-section. This damping element 13E can be preloaded by selecting its length to slightly exceed the length of its cavity 13C. In this embodiment, damping is primarily caused by the physical deformation of the elastic body 13E.

[0054] exist Figure 10 In the middle, two cylindrical damping elements 13E (made by Figure 8 The circular shape shown in the figure is arranged in a pair of adjacent cavities 13C extending axially through the damper 13. This embodiment allows for specific damping characteristics for axial loads to be transferred through the damper 13, and these specific damping characteristics can be combined with torsional damping characteristics.

[0055] Figure 11 The embodiments may be Figure 10 An alternative embodiment is described. Here, portions 135, 136, and 137 of the damper 13 are shaped to receive a pair of annular damping elements 13E. Each annular damping element 13E has an inner diameter and an outer diameter to fit within an annular cavity formed by the shape of the damper portions 135, 136, and 137.

[0056] Figure 12 and Figure 13 Other possible embodiments of the damper element 13E are shown, which can act as Figure 7 - An alternative to the implementation shown in 11. Here, various combinations of the piston structure 13P, spring 13S, and friction element 13F are used to achieve the desired damping characteristics. Figure 12In one embodiment, the piston assembly 13P is implemented as a hermetically sealed cylinder having liquid-filled chambers on either side of a piston head mounted to the end of the piston rod. A conduit through the piston head allows incompressible liquids, such as oil, to pass between the chambers on either side of the plate. Compressible fluids, such as gases, are contained in the lower chamber. A freely movable circular plate isolates this lower chamber from the liquid-filled chambers. Figure 13 In the alternative implementation shown, piston assembly 13P is implemented as an open cylinder lined with friction material 13F. An additional cylindrical body of friction material 13F is mounted to the piston rod using spring 13S. In this case, the damping characteristics are largely determined by the friction between the opposing surfaces as the piston rod moves during operation of the powertrain. The damper element described in these two figures is contained between opposing body portions 136, 137 of a torsional damper. During operation of the powertrain, axial and / or radial vibrations originating in the gearbox (and transmitted to the torsional damper via the gearbox output shaft) cause the opposing surfaces 136, 137 of the damper to deflect, thereby causing the piston rod to move within its cylinder.

[0057] Figure 14 A prior art method for suppressing structurally propagated vibrations in a cantilevered powertrain configuration is shown. Here, a torsional vibration damper 8 is arranged between a gearbox 82 and a generator 84, and is mounted around the sun shaft 820 of the last stage of the gearbox. An annular rotating plate 81 connects the damper 8 (and the output shaft 820) to a rotating bracket 83 of a bearing assembly arranged inside a sleeve 840 of the generator 82. A significant disadvantage is that it is not easy to connect a diameter D8 larger than the sleeve diameter D. 840 The damper 8 is used for maintenance. If maintenance or replacement is required at some point during the life of the wind turbine, the generator 84 and bearing assembly must be removed, and the bracket 83 must be removed to access the torsional damper 8. Furthermore, this type of damper may require connection to oil supply and drainage systems, thus introducing a further level of complexity to the powertrain.

[0058] While the invention has been disclosed by way of preferred embodiments and variations thereof, it will be understood that many additional modifications and variations can be made thereto without departing from the scope of the invention. For example, the damping element of the torsional damper can be any type of spring element with or without damping characteristics. Furthermore, the torsional damper can include any combination of the above-described damping element implementations.

[0059] For clarity, it should be understood that the use of “a” or “an” throughout this application does not exclude multiple, and “includes” does not exclude other steps or elements.

Claims

1. A wind turbine powertrain (1) comprising - a planetary gearbox (12) for converting rotation of a low speed shaft (10) to rotation of a high speed gearbox output shaft (122); - a generator (14) mounted around an annular sleeve (124) extending axially outwards from the gearbox housing (12H) and surrounding the gearbox output shaft (122); - a bearing assembly (16) arranged between the generator (14) and the gearbox (12), the bearing assembly (16) comprising a rotating bearing part (16R) and a stationary bearing part (16S); and - a torsional vibration damper (13) arranged between two rotating components (122, 122A, 122B, 14R, 16R) of the powertrain (1), the torsional vibration damper (13) comprising a plurality of damping elements (13E); characterized in that the torsional vibration damper (13) is dimensioned to facilitate access from within the generator (14).

2. The powertrain according to any one of the preceding claims, wherein, The rotating components of the powertrain (1) comprise the gearbox output shaft (10) and the rotating bearing part (16R), and wherein the torsional vibration damper (13) is arranged between a non-driving end of the gearbox output shaft (10) and the rotating bearing part (16R).

3. The powertrain of claim 2, wherein, The torsional vibration damper (13) is connected to a downwind end of the rotating bearing part (16R).

4. The powertrain of claim 2, wherein, The torsional vibration damper (13) is connected to an upwind end of the rotating bearing part (16R).

5. The powertrain according to any one of the preceding claims, wherein, The rotating components of the powertrain (1) comprise the rotating bearing part (16R) and a generator rotor (14R), and wherein the torsional vibration damper (13) is connected between the rotating bearing part (16R) and the generator rotor (14R).

6. The powertrain of any one of the preceding claims, wherein, The rotating components of the powertrain (1) comprise a first part (122A) of the gearbox output shaft (10) and a collinear second part (122B), and wherein the torsional vibration damper (13) is arranged between the output shaft parts (122A, 122B).

7. The powertrain according to any one of the preceding claims, wherein, The torsional vibration damper (13) comprises - an inner annular arrangement (132A) of threaded axial bores (132) to receive fasteners (131) for connection to a first rotating component of the powertrain (1); - an outer annular arrangement (134A) of threaded axial bores (134) to receive fasteners (133) for connection to a second rotating component of the powertrain (1); and - a plurality of damping elements (13E) between the inner annular bore arrangement (132A) and the outer annular bore arrangement (134A).

8. The powertrain according to the preceding claim, wherein, The torsional vibration damper (13) comprises a single annular damping element (13E) between the inner annular bore arrangement (132A) and the outer annular bore arrangement (134A).

9. The powertrain of claim 7, wherein, The torsional vibration damper (13) comprises a plurality of cavities (13C) between the inner annular bore arrangement (132A) and the outer annular bore arrangement (134A), and a damping element (13E) arranged in each cavity (13C).

10. The powertrain according to any one of the preceding claims, wherein, The damping element (13E) comprises any one of: an elastomeric body (13R); a spring (13S); a friction element (13F); a piston assembly (13P).

11. The powertrain according to any one of the preceding claims, wherein, The torsional damper (13) comprises an annular seal (145) arranged to prevent contaminants from entering the generator (14) and / or a bearing (180) arranged to support a cable conduit (18).

12. A method of performing a maintenance procedure on a wind turbine power train (1) according to any one of the preceding claims, the method comprising the steps of: - removing a rear cover of the generator (14); - dismounting a plurality of generator components on the upwind side of the torsional vibration damper (13) to gain access to the torsional vibration damper (13); - releasing fasteners (131, 133) of the torsional vibration damper (13); and - removing the torsional vibration damper (13) through the open rear of the generator (14).

13. The method according to the preceding claim, comprising the step of removing the bearing assembly (16) to gain access to the torsional vibration damper (13).

14. The method according to any one of the preceding method claims, comprising the step of removing a rotor support sleeve (144) to gain access to the torsional vibration damper (13).

15. The method according to any one of the preceding method claims, comprising the step of removing a generator output shaft section (122B) to gain access to the torsional vibration damper (13).

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