Torque coupling in a wind turbine generator component

Abstract

A wind turbine comprising a torque transmitting coupling between a first rotatable part and a second rotatable part, the torque transmitting coupling configured to transmit a torque about a rotational axis. The torque transmitting coupling comprises an outer ring component and an inner ring component. The outer ring component is configured to interlock with the inner ring component such that axial movement between the outer ring component and the inner ring component is constrained. A flexible coupling arrangement extends between respective axial side faces of the outer ring component and the inner ring component and is configured such that the flexible coupling arrangement transmits torque between the outer ring component and the inner ring component. An advantage of the arrangement defined above is that it improves accessibility which benefits maintenance and tuning of the stiffness of the coupling arrangement.

Description

[0001] TORQUE COUPLING IN A WIND TURBINE GENERATOR COMPONENT

[0002] Technical Field

[0003] The present invention relates to a transmission arrangement in a wind turbine.

[0004] Background to the Invention

[0005] Wind turbines convert kinetic energy from the wind into electrical energy, using a large, bladed rotor. A typical Horizontal Axis Wind Turbine (HAWT) comprises a tower, a nacelle on top of the tower, a rotor hub mounted to the nacelle and a plurality of wind turbine rotor blades coupled to the rotor hub. Depending on the direction of the wind, the nacelle and rotor blades are turned and directed into an optimal direction by a yaw system for rotating the nacelle and a pitch system for rotating the blades.

[0006] The nacelle houses many functional components of the wind turbine, including for example a main rotor shaft and one or more electrical generators, as well as convertor equipment for converting the mechanical energy at the rotor into electrical energy for provision to the grid. In some types of wind turbines, known as ‘direct drive’ systems, the main rotor shaft drives the electrical generator directly, with no intermediate gearbox. However, it is more common for wind turbines to include a gearbox to step up the rotational speed between the main rotor shaft and the electrical generator, thus converting the low speed but high torque input from the main rotor shaft to a lower torque but higher speed input into the electrical generator.

[0007] Components of the wind turbine that process and convert the rotational mechanical energy into electrical energy may be referred to as a ‘powertrain’ of the wind turbine, whereas components responsible for transmission of mechanical energy, such as the rotor and gearbox, may be referred to as the “drivetrain”.

[0008] The drivetrain emits noise during operation. Generally, it is desirable to reduce noise emissions. It is against this background that the examples of the invention have been devised.

[0009] Summary of the InventionAccording to an aspect of the invention, there is provided a wind turbine comprising a torque transmitting coupling between a first rotatable part and a second rotatable part, the torque transmitting coupling configured to transmit a torque about a rotational axis. The torque transmitting coupling comprises an outer ring component and an inner ring component. The outer ring component is configured to interlock with the inner ring component such that axial movement between the outer ring component and the inner ring component is constrained. A flexible coupling arrangement extends between respective axial side faces of the outer ring component and the inner ring component and is configured such that the flexible coupling arrangement transmits torque between the outer ring component and the inner ring component.

[0010] An advantage of the arrangement defined above is that it improves accessibility which benefits maintenance and tuning of the stiffness of the coupling arrangement. In the context of the coupling arrangement being provided as part of an electrical generator, this is particularly useful as the flexible coupling is provided inside the generator which means accessibility is improved. The coupling arrangement also provides the benefit of decoupling radial flexibility from axial flexibility.

[0011] The interlocking form between the inner ring component and the outer ring component can be formed in various ways. In one example, the interlock between the inner ring component and the outer ring component is provided at least in part by mutually-engaging radially-extending faces of the inner and outer ring components. In this respect, therefore, the inner and outer ring components are ‘keyed’ to one another so that they fit together in such a way so that relative rotational movement is permitted, but relative axial movement is not permitted.

[0012] T o benefit the relative sliding movement of the inner and outer ring components, a bearing arrangement may be provided. It is envisaged that various forms of bearing would be acceptable, such as roller bearings and the like. However, in one example, the bearing arrangement may comprise one or more friction-reducing elements located between the mutually-engaging radially-extending faces of the inner ring component and the outer ring component. The friction-reducing elements may be composed of a coating applied to at least one of the radially-extending faces of the inner ring component and the outer ring component. Such a coating may be a ‘thin-film’ coating such as may be achieved by a vapour deposition process. The friction-reducing element may also be in the form of athicker bearing pad, composed from a suitable engineering plastics, such as Nylon (RTM) or PTFE.

[0013] The one or more friction-reducing elements may be in the form of a single piece or part that extends circumferentially to provide a continuous lubricating form between sliding surfaces. Alternatively, there may be a plurality of friction-reducing elements suitably configured to provide sufficient lubricity for the application.

[0014] The functionality of the one or more friction-reducing elements may be enhanced by the provision of a lubrication chamber defined at the interlocking configuration of the inner ring component and the outer ring component. The lubrication chamber may accommodate a supply of lubrication medium such as grease and / or it may be fed actively by a ready supply of lubrication fluid, such as a natural or synthetic oil.

[0015] The interlocking form of the inner ring component and the outer ring component may also be formed at least in part by mutually-engaging axially-extending faces thereof. In such an example, one or more friction-reducing elements may also be located between the mutually-engaging axially-extending faces of the outer ring component and the inner ring component. The friction-reducing elements may be applied to either or both of the axially-extending face and the radially-extending faces of the inner and outer ring components.

[0016] The flexible coupling arrangement may be embodied by various configurations. Its main function however, is to ensure the proper transmission of torque between the inner ring component and the outer ring component. However, that transmission of torque can be achieved by providing a degree of rotational flexibility which means that a reduction in vibration is achievable. In some examples, the flexible coupling arrangement can be embodied by one or more coupling elements, the or each of the coupling elements extending between one or more attachment points on the axial side face of the outer ring component and one or more attachment points on the axial side face of the inner ring component. At least some of the coupling elements may be removable or reconfigurable so that the damping of vibrations between the inner ring component and outer ring components can be suitably adjusted, which affords the possibility to optimise the coupling. In other words, the stiffness of the rotational joint can be suitably tuned in a way that is easy to access within the confines of the assembly into which the coupling is installed.In one example, the flexible coupling arrangement can be configured to be discoidal in form, for example a frustoconical disc that attaches between the inner ring component and the outer ring component, or a part associated therewith. The frustoconical disc may be substantially solid in form but other configurations would be acceptable, such as a spoked arrangement. The flexible coupling arrangement may also take the form of a plurality of separate elements, such as arms or struts that provide the same flexible coupling function as the frustoconical disc. The flexible coupling arrangement may extend between one or more attachment points on the outer ring component and one or more attachment points on the inner ring component. So, such coupling elements may have a one-to-one relationship between inner / outer attachment points, a many-to-one relationship or a one-to-many relationship. The coupling elements may not all be identical however, and they can be ‘mixed and matched’ to configure a suitably stiff rotational interface.

[0017] The flexible coupling may be tuned to provide attenuation of certain frequencies. This may be achieved by configuring the coupling elements to permit a certain amount of angular movement under a predetermined rotational load. For example, it is envisaged that the flexible coupling may be configured to allow a range of angular movement per predetermined load of between 0.1 and 0.2 rad / MNm. This range is provided as an example as to what is currently envisaged as being a useful indication of static flexibility that changes the torsional behaviour of the coupling thereby resulting in a change in the eigenfrequencies of the rotor. This is predicted to have the result of reducing the tonality of the emitted noise.

[0018] Although in principle the torque transmitting coupling may be any size, in a particular application, it is envisaged that the inner diameter of the inner ring component may have an internal diameter of less than about 1.0m, and optionally less than about 0.7m, and greater than about 0.3m.

[0019] In a particular application, the first rotatable part may be part of a gearbox connecting hub of a generator rotor, and wherein the second rotatable part may be part of a magnetic package of the generator rotor. In this context, a utility-scale wind turbine may be considered to have a generating capacity exceeding 2MW.

[0020] Preferred and / or optional features of the invention are set out in the appended claims. It should be noted that preferred and / or optional features of the transmission of the firstaspect of the invention, as they relate to the pivot pad thereof, may also be combined with the pivot pad of the second aspect of the invention, as defined above.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Examples of the invention will now be described, by way of example only, with reference to the attached drawings, in which:

[0023] Figure 1 is a perspective view of a horizontal-axis wind turbine within which the invention may be incorporated;

[0024] Figure 2 is a perspective view of a transmission of the wind turbine in Figure 1 , into which the examples of the invention may be incorporated, the transmission arrangement including a main shaft, a gearbox and a generator;

[0025] Figure 3 is a schematic view of a cross section through the generator of the transmission;

[0026] Figure 4 is a close up view of a part of the generator shown in Figure 3;

[0027] Figure 5 is a perspective view of part of a coupling arrangement between an input drive member and a rotor of the generator.

[0028] DETAILED DESCRIPTION

[0029] A specific embodiment of the present invention will now be described in which numerous features will be discussed in detail in order to provide a thorough understanding of the inventive concept as defined in the claims. However, it will be apparent to the skilled person that the invention may be put into effect without the specific details and that in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily.

[0030] In order to place the embodiments of the invention in a suitable context, reference will firstly be made to Figure 1 , which illustrates a typical Horizontal Axis Wind Turbine (HAWT) 1 in which a transmission arrangement in accordance with examples of the invention may be implemented. Although the wind turbine is referred to as ‘horizontal axis’, it will beappreciated by the skilled person that for practical purposes, the axis is usually slightly inclined to prevent contact between the rotor blades and the wind turbine tower in the event of strong winds.

[0031] The wind turbine 1 comprises a tower 2, a nacelle 4 rotatably coupled to the top of the tower 2 by a yaw system (not shown), a rotor hub 6 mounted to the nacelle 4 and a set of wind turbine rotor blades 8 coupled to the rotor hub 6. The nacelle 4 and rotor blades 8 are turned and directed into the wind direction by the yaw system.

[0032] The nacelle 4 houses many functional components of the wind turbine, including the main rotor shaft, generator, gearbox, and power converter for converting the mechanical energy of the wind into electrical energy for provision to the grid.

[0033] The wind turbine 1 may be included in a group of wind turbines constituting a wind farm or wind park which operate collectively as a power generating plant connected by transmission lines (AC or DC) to a power grid, which may be a national or regional utility grid. The power grid comprises a network of power plants, transmission circuits, substations and breakers coupled by suitable transmission lines that transmit power to loads in the form of end users and other customers of electrical utilities.

[0034] Figure 2 illustrates an example of a layout of part of a transmission system or arrangement 18 within the nacelle 4, including a main rotor shaft or more simply ‘main shaft’ 20, which extends through a main bearing housing 22, a gearbox 24 and an electrical generator 26. The main shaft 20 is connected to, and driven by, the rotor hub 6 and provides input drive to the gearbox 24.

[0035] The gearbox 24 steps up the rotational speed of the low-speed main shaft 20 via internal gears (not shown) and drives a gearbox output drive member or “shaft” (also not shown in Figure 2). The gearbox output shaft in turn drives the electrical generator 26 (hereinafter ‘generator’), which converts the rotation of the gearbox output shaft into electricity. The electricity generated by the generator 26 may then be converted by other components (not shown) as required before being supplied to an appropriate consumer, for example an electrical grid distribution system. As shown in Figure 2, a pair of electrical conductors or ‘bus bars’ 27 are provided for power export purposes and would be connected to a suitable power converter system (not shown).The gearbox 24 may be configured in various ways. For example, in some applications epicyclic or ‘planetary’ gearboxes may be used. As the skilled person would know, an epicyclic gearbox comprises a series of planet gears that are arranged about a central sun gear, and which collectively are arranged within an encircling ring gear. The ratio of the number of teeth between the ring gear, the planet gears and the sun gear determines the gear ratio of the gearbox. For clarity, detail of the gearbox will not be described in further detail here as the gearbox is not the principal subject of the invention. Suffice to say that another gearbox configuration could also be used, although it is currently envisaged that an epicyclic gearbox provides an elegant solution suitable for the confines of a wind turbine nacelle.

[0036] Turning to the generator 26, it should be noted that the generator 26 may be configured in various ways and the type and arrangement of components within the generator 26 will depend on the particular design of generator that is used. Nonetheless, the gearbox 24 and generator 26 in the illustrated example represent what is considered a medium-speed power transmission system in the wind power industry (e.g., the generator 26 having an intended operating speed in the range of 100-500 rpm, but examples are known which may operate up to 1800-2000rpm). As illustrated in Figure 2, it will be appreciated that the gearbox 24 and the generator 26 are in a ‘closely coupled’ configuration. Also, the gearbox 24 and the main bearing housing 22 are in a similarly closely coupled configuration. More specifically, it should be noted that a gearbox housing 29 of the gearbox 24 is joined directly to the main bearing housing 22 at an annular fixing 31 comprising an array of bolts. Furthermore, the gearbox housing 29 is joined directly to a generator housing 33 of the generator 26. The generator housing 33 is generally cuboidal in shape in the illustrated example, with a substantially square geometry in end view.

[0037] An example of such a configuration is disclosed in LIS2013 / 0302144.

[0038] Also shown in Figure 2 is a support structure 36 for the main bearing housing 22. The support structure 36 is shown in dashed lines in Figure 2 and is shown here merely for context. The support structure 36 is in the form of a ‘base frame’, ‘base plate’ or ‘bed plate’, which terms are generally synonymous in this technical field, and acts as a pedestal on which rests the main bearing housing 22. Due to the close coupling of the main bearing housing 22 and the gearbox housing 29, the gearbox 24 can be considered to be suspended from the main bearing housing 22 in a cantilevered fashion. Likewise, the generator 26 can be considered to be suspended from the gearbox 24 and, thus, the mainbearing housing 22. Other forms of support can be provided to the gearbox 24 and the generator 26 but this is not essential in some applications.

[0039] Note that the main bearing housing 22 provides a wall that extends about the main shaft 20 so as to enclose it in a protective environment. The main bearing housing 22 therefore provides structural support for the main shaft 20 so that it is able to rotate, but also extends about the main shaft 20 circumferentially to provide a closed environment, open at each of its ends.

[0040] The discussion now turns to Figure 3 which shows components internal to the generator 26. Note that Figure 3 is in a simplified schematic form. Therefore, although components of the generator 26 that are pertinent to this discussion are shown, other components that may be present in a real-life generator have been omitted for clarity.

[0041] The generator 26 in the illustrated embodiment is an I PM (interior permanent magnet) electric machine having an external stator, which surrounds the rotor 32. The stator includes stator windings 38 and stator core 40. It is however noted that the invention is not limited to a specific type of stator.

[0042] The generator housing 33 is shown partially in Figure 3 as encasing the components of the generator 26.

[0043] In Figure 3, the generator rotor 32 can be seen radially inwards of the stator windings 38. The rotor 32 is supported so that it can rotate within the confines of the stator windings 38 in the conventional way. Although not seen in Figure 3, it should be appreciated that a suitable bearing arrangement may be provided that supports the rotor 32 stably within the stator windings 38 so that it is able to rotate. However, the generator 26 may also be configured so that the rotor 32 is supported for rotation by its connection to a gearbox output shaft 41 , as is shown in the configuration of Figure 3. Therefore, the rotor 32 may be considered to be supported by the gearbox 24 in a cantilevered fashion because it is only supported on one of its ends. As such, the major axis of the gearbox output shaft 41 defines the rotational axis X of the generator 26.

[0044] The rotor 32 has a non-drive end and a drive end. The non-drive end faces away from the drivetrain when the wind turbine is in use, and the drive end faces toward the drivetrain when the wind turbine is in use. The non-drive end view of the rotor 32 can be seen on theleft hand side of Figure 3, and the drive end view of the rotor 32 can be seen on the right hand side.

[0045] The rotor 32 is made up of a cylindrical ring structure 42 defining a central hollow portion or region and is arranged to rotate around a rotational axis X.

[0046] The ring structure 42 supports a set of magnetic elements (not shown). This construction of the rotor 32 therefore is able to generate a rotating magnetic field which interacts with the stator windings 38 to generate an electrical current. This is conventional technology and so will not be discussed further here, for brevity. An example of such a generator is disclosed in W02020 / 143888, to Vestas Wind Systems A / S.

[0047] The structure of the rotor 32 may be known as a ‘hollow rotor’ design due to the absence of a drive shaft 41 running the entirety of the way through the interior space of the ring structure 42. Instead, the ring structure 42 is supported by a rotor support structure 44 on one of its ends only.

[0048] The rotor support structure 44 has two ends. A first or ‘outer’ end 46 is connected to a circumferentially-extending end of the ring structure 42 and serves as a mounting point for the ring structure 42. The outer end 46 will be referred to as a ‘ring mount’ from now on.

[0049] A second or ‘inner’ end 48 provides a connecting hub 50 of the rotor 32. The connecting hub 50 is circular in this example but this is not essential. The connecting hub 50 is positioned at a radially inward position relative to the ring mount 46 of the support structure 44

[0050] A body 52 of the support structure 44 extends between the connecting hub 50 and the ring mount 46. The body 52 extends radially between the connecting hub 50 and the ring mount 46. The precise form of the body 52 is not crucial, since its main function is to support the ring mount 46 in a fixed radial position with respect to the connecting hub 50. The body 52 may therefore be in the form of a solid disk, or a set of spokes, by way of example.

[0051] The drive shaft 41 is connected between the gearbox 24 and the generator 26. More specifically, the drive shaft 41 is connected between an output of the gearbox 24 and the connecting hub 50 of the generator 26.The drive shaft 41 comprises a first end 54 and a second end 56. The first end 54 is coupled to the gearbox 24 and the second end 56 is coupled to the connecting hub 50 of the generator 26.

[0052] The drive shaft 41 may be a conventional shaft in the form of a cylindrical metal shaft (e.g. steel) of a single-piece design that extends between the first end 54 and the second end 56. The drive shaft 41 may also be of composite construction, for example a carbon fibre composite of solid or, more typically, cylindrical form.

[0053] Torque is transmitted between the drive shaft 41 and the rotor 23 by way of a torque transmitting coupling 60. An advantage of the torque transmitting coupling 60 is that it provides a degree of rotational flexibility which is configured to attenuate selected vibrational frequencies. Therefore, the torque transmitting coupling 60 can be considered to transmit torque between the drive shaft 41 and the rotor by way of a ‘soft’ connection, as will be explained in further detail in the following discussion.

[0054] In overview, the torque transmitting coupling 60 comprises the following components: an inner ring component 62, an outer ring component 64, and a flexible coupling arrangement 66 that extends between the inner ring component 62 and the outer ring component 64 and is configured to transmit torque between these components.

[0055] The inner ring component 62 and the outer ring component 64 are configured so that they are able to rotate with respect to one another about the rotational axis X is an unrestricted manner. However, the inner ring component 62 and the outer ring component 64 are configured to interlock with one another such that axial movement between the outer ring component 64 and the inner ring component 62 in the direction of the rotational axis X is constrained. An exemplary interlock feature 68 can be seen clearly in the enlarged view of Figure 4.

[0056] In the illustrated example, the interlock feature 68 is embodied by a radially extending rib or projection 70 that extends inwardly from a base part 72 of the outer ring component 64. The rib 70 may extend about the rotational X circumferentially in an unbroken manner, although this is not essential in all examples.

[0057] It should be noted at this point that the outer ring component 64 is provided by the body 52 of the connecting hub 50. In the illustrated example, the outer ring component 64 andthe body 52 are shown as different portions of the same part but they may instead be different parts and joined together in a suitable manner.

[0058] The rib 70 extends from the base part 72 into a circumferential groove 74 provided by the inner ring component 62. In this example, the groove 74 extends about the rotational axis X to provide a continuous running surface in which the rib 70 can move. It will be appreciated therefore that the rib 70 and the groove 74 provide a type of ‘rail and runner’ arrangement which allows the outer ring component 64 and the inner ring component 62 to move angularly with respect to one another, but to otherwise constrain axial movement subject to suitable engineering tolerances necessary to permit rotation.

[0059] By virtue of the configuration of the rib 70 and the groove 74, it should be appreciated that the interlock feature 68 between the inner ring component 62 and the outer ring component 64 is provided at least in part by mutually-engaging radially-extending faces of the inner and outer ring components 62,64. In this respect, therefore, the inner and outer ring components 62,64 are ‘keyed’ to one another so that they fit together in such a way so that relative rotational movement is permitted, but relative axial movement substantially is not permitted.

[0060] It will be noticed particularly from Figure 4 that the geometry of the interlock feature 68 is configured to permit a smooth sliding relationship between the components, which may be termed a ‘clearance fit’ in the art. The clearance fit may be configured so that very little axial play is permitted between the inner ring component 62 and the outer ring component 64, but rotational movement is still freely permitted (e.g. a sliding fit). Suitable lubrication can be achieved simply by way of the bare surfaces of the inner and outer ring components 62,64 in some examples where the application facilitates this.

[0061] In other examples, the clearance between the rib 70 and the groove 74 can be greater (e.g. a loose running fit) which may be useful to accommodate certain friction-reducing measures between the rib 70 and the groove 74. In this respect, to aid the lubricity between the inner ring component 62 and the outer ring component 64, a friction-reducing measure is provided by way of a bearing arrangement 80. It is envisaged that various forms of bearing would be acceptable, such as roller bearings and the like. However, in one example, the bearing arrangement 80 may comprise one or more friction-reducing elements located between the mutually-engaging radially-extending faces of the inner ring component 62 and the outer ring component 64. The friction- reducing elements may becomposed of a coating applied to at least one of the radially-extending faces of the inner ring component 62 and the outer ring component 64. Such a coating may be a ‘thin-‘film’ coating such as may be achieved by a vapour deposition process (e.g. Diamon Like Carbon or DLC) or a heat treatment process. The friction-reducing element may also be in the form of a thicker bearing pad, composed from a suitable engineering plastics, such as Nylon (RTM) or PTFE.

[0062] In the example of Figures 3 and 4, the bearing arrangement 80 is embodied by a set of bearing elements. First and second radial bearing elements 82 are provided on mutually-facing radial surfaces of the inner and outer ring components 62,64. Similarly, first and second axial bearing elements 84 are provided between mutually-facing axial surfaces of the inner and outer ring components 62,64.

[0063] A space 85 is provided in the base of the groove 74 (in this example) because the depth of the rib 70 is less than the depth of the groove 74. The space 85 can therefore serve as a lubrication chamber for a suitable lubrication medium such as a grease.

[0064] At this point it should be appreciated that the inner ring component 62 is formed from two parts, the first of which parts is labelled as 62a and the second of which is labelled 62b. Each of the two parts 62a, 62b are mirror images of each other in this example and are configured as ring-shaped components that together define a part of the groove 74. Such a configuration is convenient from a manufacturing perspective because it means that each of the parts 62a, 62b can be brought together from an axial direction to sandwich the rib 70 between parts 62a, 62b that form the groove 74.

[0065] The two parts 62a, 62b of the inner ring component 62 are joined together by a suitable first set of mechanical fasteners 86 such as an array of bolts, studs, or tie rods. As shown in this example, the fasteners 84 extend through the two parts 62a, 62b of the inner ring component 62 but also through a mounting flange 88 of the drive shaft 41 and a part of the flexible coupling arrangement 66, as will now be described.

[0066] The flexible coupling arrangement 66 has the function of ensuring the effective transmission of torque between the inner ring component 62 and the outer ring component 64. However, that transmission of torque can be achieved by providing a degree of rotational flexibility which means that a reduction in vibration is achievable. In some examples, the flexible coupling arrangement 66 can be embodied by one or more couplingelements, the or each of the coupling elements extending between one or more attachment points on the axial side face of the outer ring component 64 and one or more attachment points on the axial side face of the inner ring component 62. At least some of the coupling elements may be removable or reconfigurable so that the damping of vibrations between the inner and outer ring components can be suitably adjusted, which affords the possibility to optimise the coupling. In other words, the stiffness of the rotational joint can be suitably tuned in a way that is easy to access within the confines of the assembly into which the coupling is installed.

[0067] The flexible coupling arrangement 66 in this example is configured in the form of a substantially frustoconical body 92, which is shown in perspective view in Figure 5.

[0068] The frustoconical body 92 flares outwardly from a first end 94 to a second end 96. The first end 94 has a smaller diameter than the second end 96.

[0069] The first end 94 of the frustoconical body 92 has a first mounting feature 98 in the form of a first flange, in the illustrated example. The second end 96 of the frustoconical disc 92 has a second mounting feature 100 in the form of a second flange, in the illustrated example.

[0070] The first mounting feature 98 is attached to an axial facing surface 102 of the inner ring component 62 by the first set of mechanical fasteners 86. Similarly, the second mounting feature 100 is attached to an axial facing surface 104 associated with the outer ring component 64 by a second set of mechanical fasteners 110, which may also be selected from known fasteners such as screws, stud bolts or tie rods. In this example, the axial facing surface 104 of the outer ring component 64 is provided by an intermediate section of the body 52 which is an integral part of the outer ring component 64.

[0071] From the above discussion, it will be appreciated that the flexible coupling arrangement 66 provides the only torque load path between the drive shaft 41 and the body 52 of the connecting hub 50. The flexible coupling arrangement 66 may be tuned to provide attenuation of certain frequencies. This may be achieved by configuring the flexible coupling arrangement 66 to permit a certain amount of angular movement under a predetermined rotational load. For example, it is envisaged that the flexible coupling may be configured to allow a range of angular movement per predetermined load of between 0.1 and 0.2 rad / MNm.Although the flexible coupling arrangement 66 is formed as a solid disc in the illustrated example, this is not essential and it may instead be configured with suitable holes, grooves, areas of weaknesses or any other suitable features that are determined to provide suitable rotational flexibility.

[0072] Although in principle the flexible coupling arrangement 66 may be any size, in a particular application it is envisaged that the inner diameter of the flexible coupling arrangement 66 may be in the range of about 0.3m and about 1 ,0m (optionally less than 0.7m), merely by way of example. In contrast, the outer diameter of the flexible coupling arrangement 66 may be in the region to 1.5m to 3.0m. From this, it can be appreciated that the inner ring component 62 also may have an inner diameter in the range of about 0.3m and about 1.0m (optionally less than 0.7m).

Claims

CLAIMS1. A wind turbine comprising a torque transmitting coupling (60) between a first rotatable part (41) and a second rotatable part (52), the torque transmitting coupling configured to transmit a torque about a rotational axis(X),wherein the torque transmitting coupling comprises an outer ring component (64) and an inner ring component (62);wherein the outer ring component is configured to interlock with the inner ring component such that axial movement between the outer ring component and the inner ring component is constrained;a flexible coupling arrangement (66) extending between respective axial side faces of the outer ring component and the inner ring component and configured such that the flexible coupling arrangement transmits torque between the outer ring component and the inner ring component.

2. The wind turbine of Claim 1, wherein the interlock between the inner ring component and the outer ring component is provided at least in part by mutually-engaging radially-extending faces of the inner and outer ring components (62,64).

3. The wind turbine of Claim 2, further comprising one of more friction-reducing elements (82) located between the mutually-engaging radially-extending faces of the inner ring component (62) and the outer ring component (64).

4. The wind turbine of Claim 3, wherein the one or more friction reducing elements (82) include at least one of: a coating applied to at least one of the radially-extending faces of the inner ring component and the outer ring component, or a bearing pad.

5. The wind turbine of any one of the preceding claims, wherein the interlock between the inner ring component (62) and the outer ring component (64) is configured to provide a lubrication chamber (85).

6. The wind turbine of any one of the preceding claims, wherein the interlock between the inner ring component (62) and the outer ring component (64) is defined at least in part by mutually-engaging axially-extending faces thereof.

7. The wind turbine of Claim 6, further comprising one of more friction-reducing elements (84) located between the mutually-engaging axially-extending faces of the outer ring component and the inner ring component.

8. The wind turbine of Claim 7, wherein the one or more friction reducing elements (84) include at least one of: a coating applied to at least one of the axially-extending faces of the inner ring component and the outer ring component, a bearing pad.

9. The wind turbine of any of the preceding claims, wherein the flexible coupling arrangement (66) comprises one of more coupling elements, the or each of the coupling elements extending between one or more attachment points on the axial side face of the outer ring component and one or more attachment points on the axial side face of the inner ring component.

10. The wind turbine of Claim 9, wherein the one or more coupling elements comprises a frustoconical body (92) that extends between the inner ring component (62) and the outer ring component (64)11. The wind turbine of any one of the preceding claims, wherein the flexible coupling arrangement (66) is configured to permit relative angular movement of the outer ring component with respect to the inner ring component of 0.1 and 0.2 rad / MNm.

12. The wind turbine of any preceding claims, wherein the inner ring component has an internal diameter of at least 0.3m and about 0.7m.

13. The wind turbine of any preceding claims, wherein the inner ring component has an internal diameter of less than about 1.0m, and optionally less than about 0.7m.

14. The wind turbine of any one of the preceding claims, wherein the first rotatable part is part of a gearbox connecting hub of a generator rotor, and wherein the second rotatable part is part of a magnetic ring structure of the generator rotor.

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