Method for repairing a journal bearing assembly and journal bearing assembly of a wind turbine

Abstract

The present disclosure relates to journal bearing assemblies of wind turbines comprising a static component, a rotating component configured to rotate relative to the static component, a ring attached to either the static component or the rotating component, the ring configured to facilitate separation of a part of the ring from a remainder of the ring, and a plurality of soft bearing pad units attached to the other of the static component and rotating component The present disclosure also relates to methods for repairing journal bearing assemblies, comprising removing one or more bearing pad units having a first thickness from the static component or the rotating component, removing at least a portion of a ring mounted on the other of the static or rotating component, and positioning one or more bearing pad units having a second thickness greater than the first thickness between the static component and the rotating component.

Description

GENERAL ELECTRIC RE OVABLES ESPANA S.L. APRIL 17, 2024GE 700660- WO- 1 P5286PC00METHOD FOR REPAIRING A JOURNAL BEARING ASSEMBLY AND JOURNAL BEARING ASSEMBLY OF A WIND TURBINEFIELD

[0001] The present disclosure relates to bearing assemblies in wind turbines and more particularly to journal bearing assemblies in wind turbines and methods for repairing them. The present disclosure particularly relates to a journal bearing rotatably coupling a main rotor shaft to frame.BACKGROUND

[0002] Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly ("directly driven" or "gearless") or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

[0003] In wind turbines with a gearbox, the gearbox usually increases the speed of the wind-driven rotor and therefore the required size of the generator may be reduced. In contrast, directly driven generators, operate at the same rotational speed as the rotor. These generators, therefore, generally have a much larger diameter than generators used in wind turbines having a gearbox for providing a similar amount of power than a wind turbine with a gearbox.

[0004] A direct drive wind turbine generator may have e.g. a diameter of 6 - 10 meters (236 - 328 inches), a length of e.g. 2 - 3 meters (79 - 118 inches) and may rotate at low speed, for example in the range of 2 to 20 rpm (revolutions per minute). Alternatively, generators may also be coupled to a gearbox which increases the rotational speed of the generator to for example between 50 to 500 rpm or even more.

[0005] A generator generally comprises a rotor, a stator and an air gap separating the rotor and the stator, for example radially. The stator may be an inner structure and the rotormay surround the stator. The generator may be a permanent magnet excited generator (PMG).

[0006] Permanent magnets (PM) are generally arranged in the rotor (although they could also be alternatively arranged in the stator structure), whereas winding elements (e.g. coils) are usually included in the stator (although they could alternatively be arranged in the rotor structure). An air gap separates the permanent magnets and the coils. Permanent magnet generators are generally deemed to be reliable and require less maintenance than other generator typologies. This is an important reason why permanent magnet generator are employed in offshore wind turbines, and particularly in direct drive offshore wind turbines.

[0007] In direct drive wind turbines, a frame is generally provided on top of the tower. The frame usually supports the hub and the generator, and transfers loads to the tower. The frame, or at least a portion of a frame, is generally made of cast steel. A nacelle, which is a housing arranged on top of a wind turbine tower, may cover and protect at least a portion of the frame.

[0008] Different direct drive wind turbine topologies are known. The frame of direct drive wind turbines may rotatably support a rotating shaft and / or a generator rotor, whereas the generator stator may be directly or indirectly attached to the frame. Such a bearing assembly may also be designated as a main bearing assembly since it supports and is configured to transmit all loads due to weight, aerodynamic thrust and others to the frame, and then further to the tower.

[0009] Generally, one or more roller bearings are used in such a bearing assembly, e.g. double tapered roller bearing. Roller bearings may comprise balls or rollers arranged between an inner ring and an outer ring for reducing the friction between these rings.

[0010] These bearing assemblies can be very expensive because of the low tolerances required and high loads that they need to withstand. Maintenance of the main bearing assembly in direct drive wind turbine topologies can be very complicated and may require complete overhaul of the machine head: the complete rotor may need to be removed as different components cannot be separated from each other on site. Particularly in offshore wind turbines this sort of maintenance is very costly.

[0011] Journal bearings or sliding bearings form an alternative for roller bearings, and they are known to be cheaper than roller bearings and to withstand high loads in axial and radial directions. Sliding bearings comprise sliding pads which are usually wedge shaped. Such bearings may also be called plain bearings.

[0012] During normal operation of a bearing, over time, the different components comprising the bearing assembly can suffer from wear and also from damage due to loadsand forces from the wind acting on the wind turbine, in particular in heavy wind turbines, e.g. offshore wind turbines.

[0013] The bearing components may thus need to be repaired or replaced. It is known to use journal bearings comprising a segmented shell or tilting pads. In case of damage, it is known to rotate the sliding pads out of the load zone or to dismount them while the system is supported and fixed by temporary means. Such a method in a wind turbine can allow for repair of the sliding pads uptower and without the use of cranes.

[0014] However, damage to the other bearing components is unrepairable uptower, and often requires the whole system to be disassembled and taken to a workshop, where it may be repaired. This is a very expensive task, which in addition takes a lot of time. The magnitude of the problem increases for offshore wind turbines.

[0015] The present disclosure provides systems and methods to at least partially overcome some of the aforementioned drawbacks.SUMMARY

[0016] In an aspect of the present disclosure, a method for repairing a journal bearing assembly of a wind turbine is provided. The journal bearing assembly comprises a static component and a rotating component. The method comprises removing one or more bearing pad units having a first thickness from either the static component or the rotating component. The method further comprises removing at least a portion of a ring mounted on the other of the static component or rotating component, and positioning one or more bearing pad units having a second thickness between the static component and the rotating component. The second thickness is greater than the first thickness.

[0017] According to this aspect, an unrepairable damage e.g. due to wear of the static or rotating components may be avoided and the bearing assembly may be repaired uptower. The method allows the extension of the life of the journal bearing assembly in an efficient and cost-effective way, since a damaged portion of a component of the bearing assembly may not lead to an entire dismantling of the upper section of the wind turbine.

[0018] In another aspect of the present disclosure, a journal bearing assembly for a wind turbine is provided. The journal bearing assembly comprises a static component, a rotating component configured to rotate relative to the static component and a ring attached to either the static component or the rotating component. The journal bearing assembly further comprises a plurality of soft bearing pad units attached to the other of the static componentand the rotating component. The ring is configured to facilitate separation of a part of the ring from a remainder of the ring.

[0019] The static or rotating components may be protected by the ring, which will be the component in contact with the bearing pad units. The ring may eventually wear down and need to be repaired. The journal bearing assembly of the present disclosure provides a bearing assembly comprising a component which may protect the other components and which may be removed uptower, allowing further functioning of the bearing assembly without the need of dismantling it, and therefore allowing to save a lot of effort and resources.

[0020] In a furtheraspect of the disclosure a direct-drive wind turbine comprising a bearing assembly for a wind turbine is provided. The bearing assembly comprises a rotatable shaft coupled to a wind turbine hub, a frame configured to rotatably support the rotatable shaft, one or more bearing pad units attached to the rotatable shaft, and an inner ring attached to the frame. The inner ring is configured to facilitate separation of a part of the ring from a remainder of the ring.

[0021] Additional objects, advantages and features of embodiments of the present disclosure will become apparent to those skilled in the art upon examination of the description, or may be learned by practice.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 schematically illustrates a perspective view of one example of a wind turbine;

[0023] Figure 2 illustrates an example of a hub and a nacelle of a wind turbine;

[0024] Figure 3 shows a flow chart of an example of a method for repairing a journal bearing assembly of a wind turbine;

[0025] Figure 4 schematically illustrates a cross-section of a journal bearing assembly according to an example of the present disclosure;

[0026] Figures 5a and 5b schematically illustrate examples of bearing pad units having a first and a second thickness according to an example of the present disclosure; and

[0027] Figure 6 schematically shows a cross-section of the repaired journal bearing assembly of figure 4.DETAILED DESCRIPTION OF EXAMPLES

[0028] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the teaching. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0029] Figure 1 is a perspective view of an example of a wind turbine 10. In the example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In the example, the wind turbine 10 includes a tower 15 that extends from a support system 14 on a ground 12, a nacelle 16 mounted on tower 15, and a rotor 18 that is coupled to nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outward from the hub 20. In the example, the rotor 18 has three rotor blades 22. In an alternative embodiment, the rotor 18 includes more or less than three rotor blades 22. The tower 15 may be fabricated from tubular steel to define a cavity (not shown in figure 1) between a support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of a tower having any suitable height. According to an alternative, the tower can be a hybrid tower comprising a portion made of concrete and a tubular steel portion. Also, the tower can be a partial or full lattice tower.

[0030] The rotor blades 22 are spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. The rotor blades 22 are mated to the hub 20 by coupling a blade root portion 24 to the hub 20 at a plurality of load transfer regions 26. The load transfer regions 26 may have a hub load transfer region and a blade load transfer region (both not shown in figure 1). Loads induced to the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0031] In examples, the rotor blades 22 may have a length ranging from about 15 meters (m) to about 90 m or more. Rotor blades 22 may have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include 20 m or less, 37 m, 48.7 m, 50.2m, 52.2 m or a length that is greater than 91 m. As wind strikes the rotor blades 22 from a wind direction 28, the rotor 18 is rotated about a rotor axis 30. As the rotor blades 22 are rotated and subjected to centrifugal forces, the rotor blades 22 are also subjected to various forces and moments. As such, the rotor blades 22 may deflect and / or rotate from a neutral, or non-deflected, position to a deflected position.

[0032] Moreover, a pitch angle of the rotor blades 22, i.e., an angle that determines an orientation of the rotor blades 22 with respect to the wind direction, may be changed by a pitch system 32 to control the load and power generated by the wind turbine 10 by adjusting an angular position of at least one rotor blade 22 relative to wind vectors. Pitch axes 34 of rotor blades 22 are shown. During operation of the wind turbine 10, the pitch system 32 may particularly change a pitch angle of the rotor blades 22 such that the angle of attack of (portions of) the rotor blades are reduced, which facilitates reducing a rotational speed and / or facilitates a stall of the rotor 18.

[0033] In the example, a blade pitch of each rotor blade 22 is controlled individually by a wind turbine controller 36 or by a pitch control system 80. Alternatively, the blade pitch for all rotor blades 22 may be controlled simultaneously by said control systems.

[0034] Further, in the example, as the wind direction 28 changes, a nacelle 16 may be rotated about a yaw axis 38 to position the rotor blades 22 with respect to wind direction 28.

[0035] In the example, the wind turbine controller 36 is shown as being centralized within the nacelle 16, however, the wind turbine controller 36 may be a distributed system throughout the wind turbine 10, on the support system 14, within a wind farm, and / or at a remote-control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. Further, many of the other components described herein include a processor.

[0036] As used herein, the term “processor” is not limited to integrated circuits referred to in the art as a computer, but broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific, integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or a control system can also include memory, input channels, and / or output channels.

[0037] The wind turbine 10 of figure 1 may be placed in an offshore or onshore location. The wind turbine of figure 1 may be a direct-drive wind turbine.

[0038] Figure 2 illustrates a simplified, internal cross-sectional view of the nacelle 161 and the rotor hub 110 of a direct-drive wind turbine 160 such as the one shown in figure 1 . Some elements of the wind turbine 160 have not been illustrated for the sake of clarity. As shown, the generator 3 may be coupled to the rotor hub 110 of the wind turbine 160 for generating electrical power from the rotational energy generated. Thus, rotation of the rotor hub 110 drives the generator 3.

[0039] It should be appreciated that frame 1 and generator 3 may generally be supported by a support frame or bedplate 17 positioned atop the wind turbine tower 170. The bedplate 17 may be a bottom portion or may be joined to a bottom flange of a frame 1. The nacelle 161 is rotatably coupled to the tower 170. The bedplate 17 may be rotatably coupled to a wind turbine tower 170.

[0040] The direct-drive wind turbine 160 of figure 2 comprises a generator 3 mounted on a frame 1. The generator 3 comprises a generator stator 32 and a generator rotor 31 configured to rotate about a rotation axis RA. The frame 1 has a rear portion 16 and a front or protruding portion 11 . The protruding portion 11 may be integrally formed with the rear portion 16 or may be separate from the rear portion 16. If separate formed, fasteners 4 such as bolts may attach the front 11 and rear 16 portions of the frame 1. The protruding portion 11 extends beyond the generator 3. The rear portion 16 is provided between the front portion 11 and the tower 170.

[0041] A rear portion 16 of the frame 1 may be called main frame 16. A main frame may transfer the loads and the vibrations acting on the rotor 115 of a wind turbine 160 to the tower 170 of the wind turbine 160. A main frame may be made of cast steel. A main frame may have a bottom opening, a front opening and a rear opening. The bottom opening may enable passage between the main frame and an inside of the tower 170, the front opening may enable passage between the main frame and an inside 111 of the rotor hub 110, e.g. through a front portion 11 , and the rear opening may enable passage between the main frame and an inside of the nacelle 161.

[0042] In figure 2, the protruding portion 11 extends towards the rotor hub 110 of the wind turbine 160 along the rotation axis RA. Thus, the protruding portion 11 may extend in an upwind direction along the rotation axis RA. At least a part of the protruding portion 11 may be placed in a room 111 defined inside the rotor hub 110. The room 111 may be defined as the hollow body of the rotor hub 110.

[0043] A protruding portion 11 of the frame 1 may comprise a first structure and a second structure. The first and second structures are configured to rotate relative to each other and about the rotation axis RA. The first structure may be attached to the generator stator 32 and the second structure may be attached to the generator rotor 31. The terms first are second are interchangeably herein.

[0044] In figure 2, the first structure is an inner structure 13 and the second structure is an outer structure 12. In another example, the first structure may be an outer structure and the second structure may be an inner structure. In both examples the inner and the outer structure may rotate relative to each other and about the rotation axis RA.

[0045] The outer structure 12 may be operatively connected to the rotor hub 110 through the generator rotor 31 . The latter may be achieved, for instance, through a series of bolts 4. The bolts 4 may join together the rotor hub 110, the outer structure 12 and the generator rotor 31 in such a way that at least a part of the generator rotor 31 is sandwiched by the rotor hub 110 and the outer structure 12. This exemplary joint may allow to transmit the rotating movement of the rotor hub 110 to the outer structure 12 through the generator rotor 31. Conversely, if for example the outer structure 12 is braked, then the generator rotor 31 and the rotor hub 110 may be braked as well. In another example, the joint may be achieved through any fasteners available on the market or even through welding.

[0046] The first structure, e.g. the inner structure 13, may have a tapered region 18 towards the rotor hub 110. The second structure, e.g. the outer structure 12, may be rotatably mounted on the tapered region 18. I.e. , the second structure can rotate about the rotation axis RA and the first structure. The tapered region 18 may protrude from the generator 3, at least partially, towards the rotor hub 110.

[0047] Further, the front portion 11 of the frame may comprise a journal bearing assembly 18 comprising a first bearing component 17 attached to the generator stator 32 and a second bearing component 12 attached to the generator rotor 31. The first bearing component and the second bearing component are configured to rotate relative to each other.

[0048] Accordingly, the second bearing component 12 may be operatively connected to the rotor hub 110 through the generator rotor 31 e.g. through a series of bolts. The joint may allow to transmit the rotating movement of the rotor hub 110 to the second bearing component 12 through the generator rotor 31 . Conversely, if for example the second bearing component 12 is braked, then the generator rotor 31 and the rotor hub 110 may be braked as well.

[0049] In an aspect of the present disclosure, a method 300 for repairing a journal bearing assembly of a wind turbine is provided. The journal bearing assembly comprises a static component and a rotating component.

[0050] Figure 3 shows a flow chart of the method 300 according to an example of the present disclosure.

[0051] The method 300 comprises, at step 302, removing one or more bearing pad units having a first thickness from either the static component or the rotating component, at step 304, removing at least a portion of a ring mounted on the other of the static component or the rotating component, and at step 306, positioning one or more bearing pad units having a second thickness between the static component and the rotating component. The second thickness is greater than the first thickness.

[0052] The operation of the journal bearing assembly may lead to damage e.g. wear of some of its components. The present method provides a way of repairing a journal bearing assembly uptower, avoiding the need of disassembling the upper structure of the wind turbine such that it may be repaired. A correct functioning of the journal bearing assembly may then be ensured in a more efficient and cost-effective manner.

[0053] Figure 4 schematically shows an example of a cross-section of a journal bearing assembly 18 according to an example of the present disclosure.

[0054] The journal bearing assembly 18 comprises a static component 17, a rotating component 12 which is configured to rotate relative to the static component 17 and a ring 13 attached to either the static component 17 or the rotating component 12.

[0055] The static component 17 may be formed of cast iron. Further, the ring 13 may be a cast iron ring or a steel ring. The ring 13 may be a hard ring. The ring 13 of the journal bearing assembly 18 may comprise a surface which may be configured to contact one or more bearing pad units.

[0056] As shown in the example of figure 4, the static component 17 may be a front frame 11 of the wind turbine which supports the generator 3 and the hub 110, and the ring 13 of the journal bearing assembly 18 may be shrunk on the front frame 11 .

[0057] In other examples, the ring 13 may be shrunk on the rotating component 12. In some examples the rotating component 12 may be a rotating shaft, rotatably mounted on and radially surrounding the static frame 11 .

[0058] The journal bearing assembly 18 further comprises a plurality of bearing pad units 15 arranged between the static component 17 and the rotating component 12. The bearing pad units may be soft bearing pads 15.

[0059] The bearing pad units 15 may be arranged in an annular way and may ensure rotation of the rotating component relative to the static component, reducing the friction between them. The static component 17 and the rotating component 12 may exert pressure on the plurality of bearing pad units 15 which may be clamped between these components. Accordingly, the bearing pad units 15 may be able to withstand high loads.

[0060] In some examples, as shown in figure 4, the bearing or sliding pad units may be an assembly comprising a base (e.g. with a socket), a ball element, and a contact layer. In other examples, the bearing or sliding pad units may be wedge shaped.

[0061] Further, the ring 13 is configured to facilitate separation of a part of the ring from a remainder of the ring.

[0062] During normal operation of the wind turbine, the ring 13, mounted on the static or the rotating component, and in contact with the bearing pad units may suffer from wear which may lead to a malfunction of the wind turbine. In particular, at least a part of the ring 13 in contact with the bearing pad units may wear down. A ring which is configured to facilitate separation of a part of the ring may provide longer life span to the wind turbine and may avoid having to disassemble it in order to repair damaged static and / or rotating components.

[0063] In further examples, the method 300 may comprise mechanically locking the wind turbine rotor using locking pins. I.e. one or more locking pins may enter corresponding holes on a locking plate operatively connected to the wind turbine rotor such that the rotor is locked. E.g. a locking plate with 6 or more holes may be provided.

[0064] In some examples, the method 300 for repairing the journal bearing assembly 18 may comprise identifying a damaged component of the journal bearing assembly. In some examples, the damaged component may be the ring 13 attached to either the static component 17 or the rotating component 12. A damaged ring may refer to a worn ring. In other examples, a damaged ring may refer to any other condition of the ring caused while operating the wind turbine and which may lead to a malfunction of the whole journal bearing assembly.

[0065] The method 300 for repairing a journal bearing assembly may further comprise unloading one of the bearing pad units 15 before removing the bearing pad unit 15 from the journal bearing assembly. Unloading the bearing pad unit i.e. releasing a pressure on the bearing pad unit, may facilitate removal of the bearing pad unit.

[0066] In some examples, unloading one of the bearing pad units may comprise exerting axial and radial forces between a part of the static structure and the rotating component or shaft using especial tools.

[0067] In some examples, unloading the bearing pad unit may comprise the use of one or more jacks. The jacks may be applied between the shaft and the front frame 11 of the wind turbine. In further examples, jacks or other apparatus may be used to axially push or pull the locking plate to compensate a bending moment caused by the weight of the rotor.

[0068] Once the bearing pad unit may be unloaded, the method 300 comprises, at step 302, removing one or more bearing pad units 15 having a first thickness from either the static component or the rotating component. Removing the bearing pad unit may allow access to a portion of the ring. In some examples, the portion of the ring may be damaged e.g. worn.

[0069] In some examples, the rotating component may be a rotating shaft, rotatably mounted on and radially surrounding a static frame.

[0070] The method further comprises, at step 304, removing at least a portion of a ring 13 mounted on the other of the static component 17 or rotating component 12. Removing at least a portion of the ring may comprise creating a hollow space in the ring.

[0071] In some examples, removing at least a portion of the ring may comprise completely removing the ring. In these examples, the ring 13 may be configured to be cut in pieces. A piece or portion of the ring 13 may be regarded as one of the sections of the ring that together form the entirety of the ring.

[0072] In these examples, removing at least a portion of the ring may comprise cutting off at least a portion of the ring. In some examples, cutting off the portion of the ring may comprise the use of a tool arranged in a space created by removal of one of the bearing pad units. Cutting tools known in the art may be used to cut the portion of the ring off.

[0073] In some examples, when the cutting tool has almost reached a side of the ring opposite to the side which was in contact with the bearing pad units, the ring may crack due to a high hoop stress created in the ring.

[0074] In some examples, the ring 13 may comprise one or more grooves 131. The grooves may make the process of cutting off the ring easier.

[0075] In some examples, the grooves may be arranged throughout the ring. Further, the grooves 131 may be axial grooves. The axial grooves may have a rounded cross-section.

[0076] In some examples, the grooves may be run-out grooves. Providing a ring with runout grooves may prevent a cutting operation from damaging any component which may be adjacent to the ring and which should not be cut e.g. the static or rotating components.

[0077] In further examples, the ring 13 may be made of a plurality of laminations, and the laminations forming the ring 13 may be configured to be separated from one another.

[0078] In these examples, removing at least a portion of the ring may comprise removing a layer of the ring 13. In some examples, a plurality of layers of the laminated ring may be worn, and the method may comprise removing or stripping the plurality of the layers of the laminated ring e.g. removing 3 or 4 layers.

[0079] The method 300 may further comprise cleaning and / or polishing the space left where the removed portion of the ring used to be i.e. a hollow space.

[0080] Further, step 306 of the method comprises positioning one or more bearing pad units 15’ having a second thickness between the static component and the rotating component.

[0081] The one or more bearing pad units 15’ having a second thickness may fill the hollow space left after removing the bearing pad unit 15 having a first thickness and the portion of the ring, once again reducing a friction between the static and rotating components during the wind turbine operation.

[0082] The bearing pad units 15 have a first thickness and the bearing pad units 15’ have a second thickness which is greater than the first thickness.

[0083] Figure 5a schematically represents a bearing pad unit 15 having a first thickness and figure 5b schematically represents a bearing pad unit 15’ having a second thickness according to an example of the present disclosure. In this particular example, the bearing pad units are assemblies comprising a base 152, 152’, a ball element 151 , 15T and a contact layer 153, 153’ configured to contact the static component. However, other configurations of bearing pad units may be possible e.g. one-piece wedge-shaped bearing pad units.

[0084] As may be appreciated in figures 5a and 5b, the base 152’ of the bearing pad unit 15’ comprises greater thickness than the base 152 of the bearing pad unit 15. The overall second thickness of the bearing pad units 15’ may correspond to a sum of the first thickness of the bearing pad units 15 and the thickness of the hollow space created in the ring 13 after removing a portion of it.

[0085] In some examples, removing one or more bearing pad units 15 having a first thickness may comprise removing one or more first bearing pad units and positioning one or more bearing pad units 15’ having a second thickness may comprise positioning one or more second bearing pad units.

[0086] In these examples, the first bearing pad units 15 and the second bearing pad units 15’ may be different bearing pad units, i.e. the first bearings pad units 15 may be substituted by second bearing pad units 15’ having an overall second thickness which is higher than the first thickness. Thereby the second bearing pad units occupy the space previously occupied by the first bearing pad units and (the portion of) the ring that has been removed. The second bearing pad units may have a curvature adapted to the curvature of the remaining portion of the ring or the component without the ring.

[0087] In other examples, removing one or more bearing pad units 15 having a first thickness may comprise removing one or more first bearing pad units, and positioning one or more bearing pad units 15’ with a second thickness may comprise positioning the first bearing pad units and an additional filler element.

[0088] I.e. in this example, the same bearing pad units may be reused. The filler element may have a thickness corresponding to the hollow space created in the ring 13 after removinga portion of it. Depending on the circumstances, the curvature of the bearing pads may been to be adjusted.

[0089] In yet further examples, removing one or more bearing pad units 15 having a first thickness may comprise removing one or more first bearing pad units and positioning one or more bearing pad units 15’ having a second thickness may comprise reshaping the first bearing pad units and positioning the first bearing pad units.

[0090] Accordingly, the bearing pad units 15 may be reshaped after removing them from the static or rotating component, and the step of positioning bearing pad units 15’ having a second thickness may comprise positioning the reshaped bearing pad units between the static and the rotating component.

[0091] Reshaping the first bearing pad units may comprise adapting their overall thickness such that the reshaped bearing pad units have a second thickness greater than the first thickness of the bearing pad units i.e. their thickness before being reshaped. Depending on the type of bearing pad unit used e.g. number of components and material, the thickness of the bearing pad unit may be modified in different ways. In some examples, additional material may be added to the bearing pad unit to increase its overall thickness e.g. a filler may be added adhesively to a base or to a contact layer of the bearing pad unit.

[0092] Further, reshaping the first bearing pad units may also comprise adapting the curvature of the surface of the bearing pad unit contacting the static or rotating component, as the curvature of the component will have changed due to the removal of the ring portion.

[0093] Accordingly, in these examples, positioning one or more bearing pad units 15’ having a second thickness may comprise positioning the one or more first bearing pad units 15 after their thickness has been increased i.e. positioning the reshaped bearing pad units having an additional thickness portion corresponding to the hollow space created in the ring after removing a portion of it.

[0094] The method 300 may further comprise repeating the method steps until the process has been carried out for every single bearing pad unit 15 of the journal bearing assembly.

[0095] In some examples e.g. where the method comprises removing a layer of the ring, after reparation of the journal bearing assembly the ring mounted on the static component or the rotating component may comprise an overall smaller thickness than it did before the reparation took place.

[0096] In other examples e.g. where portions of the ring have been cut off, bearing pad units 15‘ having a second thickness may replace the entire ring which was previously mounted on the static component or the rotating component.

[0097] It is noted that even though figure 3 illustrates the method as being carried out with a specific order of steps, it is noted that the order of steps should not be regarded as limiting. I.e. it is possible to carry out more than one step simultaneously, and it is possible in some examples to change the order of the steps.

[0098] Figure 6 schematically shows a cross section of the repaired journal bearing assembly shown in figure 4 according to an example.

[0099] As may be seen, the repaired journal bearing assembly 18 no longer comprises the iron ring mounted on the static component 17. In addition, the space originally occupied by the cast iron ring in figure 4 is now occupied by bearing pad units 15’, which comprise greater thickness than the first bearing pad units of figure 4.

[0100] Figure 6 therefore shows a journal bearing assembly 18 which has been repaired uptower.

[0101] In a further aspect of the present disclosure, a direct-drive wind turbine comprising a bearing assembly 18 for a wind turbine is disclosed. The bearing assembly comprises a rotatable shaft 12 coupled to a wind turbine hub 110, a frame 17 configured to rotatably support the rotatable shaft 12, one or more bearing pad units 15 attached to the rotatable shaft 12, and an inner ring 13 attached to the frame 17. The inner ring 13 is configured to facilitate separation of a part of the ring from a remainder of the ring.

[0102] In some examples, the inner ring 13 may be shrunk fit on the frame 17. In other examples, the inner ring 13 may be shrunk fit on the rotatable shaft 12.

[0103] The inner ring 13 may be a cast iron ring or a steel ring. In some examples, the inner ring 13 may comprise a plurality of axial grooves 131. In other examples, the ring may be made of a plurality of laminations and the laminations may be configured to be separated from one another.

[0104] In some examples, the rotatable shaft 12 may be coupled to a rotor of a generator 31.

[0105] This written description uses examples to disclose the teaching, including the preferred embodiments, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well asother known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A method (300) for repairing a journal bearing assembly (18) of a wind turbine, comprising a static component (17) and a rotating component (12), the method comprising: removing (302) one or more bearing pad units (15) having a first thickness from either the static component (17) or the rotating component (12); removing (304) at least a portion of a ring (13) mounted on the other of the static component (17) or rotating component (12); and positioning (306) one or more bearing pad units (15’) having a second thickness between the static component (17) and the rotating component (12), wherein the second thickness is greater than the first thickness.

2. The method of claim 1 , wherein removing one or more bearing pad units (15) having a first thickness comprises removing one or more first bearing pad units and wherein positioning one or more bearing pad units (15’) with a second thickness comprises positioning one or more second bearing pad units.

3. The method of claim 1 , wherein removing one or more bearing pad units (15) having a first thickness comprises removing one or more first bearing pad units and wherein positioning one or more bearing pad units with a second thickness (15’) comprises positioning the first bearing pad units and an additional filler element.

4. The method of claim 1 , wherein removing one or more bearing pad units (15) having a first thickness comprises removing one or more first bearing pad units and wherein positioning one or more bearing pad units (15’) with a second thickness comprises reshaping the first bearing pad units and positioning the first bearing pad units.

5. The method (300) of any of claims 1 - 4 wherein removing at least a portion of the ring comprises removing a layer of the ring.

6. The method (300) of any of claims 1 - 4, wherein removing at least a portion of the ring comprises completely removing the ring.

7. The method (300) of any of claims 1 - 6, wherein removing at least a portion of the ring comprises cutting off the portion of the ring.

8. The method (300) of claim 7, wherein cutting off the portion of the ring comprises use of a tool arranged in a space created by removal of one of the bearing pads units (15).

9. The method (300) of any of claims 1 - 8, comprising unloading one of the bearing pad units (15) before removing the bearing pad units (15) from the journal bearing assembly (18), and optionally wherein unloading one of the bearing pad units comprises the use of one or more jacks.

10. The method (300) of any of claims 1 - 9, wherein the rotating component (12) is a rotating shaft, rotatably mounted on and radially surrounding a static frame (11).

11. A journal bearing assembly (18) of a wind turbine, comprising: a static component (17); a rotating component (12), configured to rotate relative to the static component (17); a ring (13) attached to either the static component (17) or the rotating component (12); and a plurality of soft bearing pad units (15) attached to the other of the static component (17) and rotating component (12), wherein the ring (13) is configured to facilitate separation of a part of the ring from a remainder of the ring.

12. The journal bearing assembly (18) of claim 11 , wherein the ring (13) is configured to be cut in pieces, particularly wherein the ring (18) comprises one or more grooves (131).

13. The journal bearing assembly (18) of claim 12, wherein the grooves (131) are axial grooves, and specifically wherein the axial grooves have a rounded cross-section.

14. The journal bearing assembly (18) of any of claims 11 - 13, wherein the ring (13) is made of a plurality of laminations, and wherein the laminations are configured to be separated from one another.

15. A direct-drive wind turbine (160) comprising: a rotatable shaft (12) coupled to a wind turbine hub (110); a frame (17) configured to rotatably support the rotatable shaft (12); and the journal bearing assembly of any of claims 10 - 14, wherein the bearing pad units (15) are attached to the rotatable shaft (12); and the inner ring (13) is attached to the frame (17).

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