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

Abstract

Journal bearing assembly for wind turbines comprising a static component (17), a rotating component (12) configured to rotate relative to the static component, a ring (13) mounted on the static component, and a plurality of bearing pads (15) mounted on the rotating component. The ring is configured to provide a clearance between the ring and the bearing pads in an area that is substantially unloaded by a weight of the wind turbine rotor. Method for repairing a journal bearing assembly of a wind turbine, comprising selecting a first bearing pad to be removed, positioning the first bearing pad in a removal position, the removal position being in an area of the journal bearing assembly that is substantially unloaded by a weight of the wind turbine rotor, locking the rotating component and maintaining the first bearing pad in the removal position and removing the first bearing pad through a clearance created in a ring mounted on the static component.

Description

GENERAL ELECTRIC RE OVABLES ESPANA S.L. AUGUST 14, 2024GE 700948- WO- 1 P5454PC00METHOD FOR REPARING 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 journal bearing assemblies. 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 from the wind turbine rotor 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 e.g. jack systems. Such a method in a wind turbine can allow for repair of the sliding pads uptower and without the use of cranes.

[0014] The present disclosure provides systems and methods to at least partially overcome some of the aforementioned drawbacks.SUMMARY

[0015] 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 rotating component operatively connected to a wind turbine rotor, and a static component supporting the rotating component. The method comprises selecting a first bearing pad to be removed, the first bearing pad being mounted on the rotatable component, and positioning the first bearing pad in a removal position, the removal position being in an area of the journal bearing assembly that is substantially unloaded by a weight of the wind turbine rotor. The method further comprises locking the rotating component and maintaining the first bearing pad in the removal position, and removing the first bearing pad through a clearance created in a ring mounted on the static component.

[0016] According to this aspect, a bearing pad may be removed and exchanged from a journal bearing assembly of a wind turbine uptower and without the use of heavy lifting tools that lift the entire weight of the rotor, which is burdensome, and which results in the transmission of enormous loads from the static frame to the wind turbine tower. Exchanging the soft bearing pads is facilitated and possible at lower cost. A significant advantage of a journal bearing assembly in this sense is that it can be repaired in situ i.e. without requiring a complete overhaul of the wind turbine rotor and / or drive train.

[0017] In prior art journal bearings, the static component and the rotating component of the journal bearing assembly exert pressure on the plurality of bearing pads, which are clamped between these components. Contrary to prior art configurations, in the present case, the ring is mounted on the static component of the journal bearing, whereas the bearing pads are arranged with the rotating component.

[0018] The present method allows to use a substantially unloaded area of the journal bearing to unload or release a pressure on the bearing pad which is to be removed without using any lifting tools. This is achieved through a clearance created in a substantially unloaded area of a ring mounted on the static component.

[0019] The rotating component and the ring exert pressure on the bearing pads, however, with the created clearance, the bearing pads do not contact the area of the ring which is substantially unloaded by the weight of the wind turbine rotor. Accordingly, the clearance prevents the bearing pad arranged in the same radial direction from contacting the static part of the bearing i.e. from contacting the ring attached to the static component, substantially releasing a pressure on the pad. Further, the clearance in the substantially unloaded area of the ring acts as a window, which creates the required space for the extraction of a soft bearing pad. The clearance in the ring allows accessing the bearing pads without the need of lifting the journal bearing with lifting tools.

[0020] The rotating component may then be locked, and the weight of the rotor may be used to support the rotating part in the removal position, and therefore to maintain the bearing pad to be removed in the removal position. The method allows access to and exchange of the soft bearing pads of the journal bearing uptower without the need of using heavy cranes that lift the entire weight of the rotor of the wind turbine to release the pressure on the pad.

[0021] The journal bearing assembly of the wind turbine is under multiple loads, and different parts of the journal bearing assembly may be under different loads. Throughout the present disclosure, an area that is substantially unloaded by a weight of the wind turbine rotor may be regarded as an area of the journal bearing assembly which is under less loads due to the weight of the rotor as compared to other areas of the bearing. The rotatable component that is operatively connected to the wind turbine rotor will experience a deflection due to the weight of the rotor that is either upward or downwards depending on the location of the journal bearing assembly. The area that is substantially unloaded by weight of the wind turbine rotor may be regarded as a circular segment having a central angle of 180 degrees or less, specifically 90 degrees or less, and more specifically 45 degrees or less which is located at the opposite side of the deflection experienced by the rotatable component.

[0022] A wind turbine rotor including hub and a plurality of blades is generally arranged upwind from the nacelle. The wind turbine rotor represents a very significant weight, and thus causes a (constant) forward bending load on the bearing(s) i.e. the wind turbine rotor has a tendency to tilt the wind turbine forward.

[0023] Accordingly, both the upwind area of the journal bearing and the downwind area of the journal bearing have an area that is substantially unloaded i.e. an area in the downwindbearing which is under less rotor loads than the rest of the areas in the downwind bearing, and an area in the upwind bearing which is under less rotor loads than the rest of the areas in the upwind bearing.

[0024] Throughout the present disclosure, a clearance may be regarded as an opening. A clearance in a substantially unloaded area of the ring may be regarded as an opening in the ring which may allow direct access to the soft bearing pads of the journal bearing assembly.

[0025] 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 operatively connected to the wind turbine rotor, configured to rotate relative to the static component and a ring mounted on the static component. The journal bearing assembly further comprises a plurality of bearing pads mounted on the rotating component. The ring is configured to provide a clearance between the ring and the bearing pads in an area that is substantially unloaded by a weight of the wind turbine rotor.

[0026] In a further aspect of the disclosure a wind turbine is provided. The wind turbine comprises a wind turbine rotor including a hub and a plurality of blades, a rotating shaft operatively connected to the wind turbine rotor and a static frame supporting the rotating shaft. The wind turbine further comprises an upwind journal bearing assembly and a downwind journal bearing assembly including a ring mounted on the static frame, and a plurality of bearing pads on the rotating shaft. The rotating shaft radially surrounds the static frame, and the ring of the upwind journal bearing assembly is configured to provide a clearance between the ring and the bearing pads substantially in a 6 o’clock position and / or the ring of the downwind journal bearing assembly is configured to provide a clearance between the ring and the bearing pads substantially in a 12 o’clock position.

[0027] Due to the effect of the bending load caused by the weight of an upwind wind turbine rotor, an upwind bearing may have a substantially unloaded area at the top i.e. at or near a 6 o'clock position, whereas for a downwind bearing this may be at a bottom i.e. at or near a 12 o’clock position in case the rotating shaft surrounds the static frame.

[0028] 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

[0029] Figure 1 schematically illustrates a perspective view of one example of a wind turbine;

[0030] Figure 2 illustrates a simplified internal cross-sectional view of an example of a hub and a nacelle of a wind turbine;

[0031] Figure 3 shows a flow chart of an example of a method for removing a soft bearing pad of a journal bearing assembly of a wind turbine;

[0032] Figure 4 schematically shows a cross-sectional view of a direct drive wind turbine comprising a journal bearing assembly according to an example of the present disclosure;

[0033] Figure 5 schematically illustrates a cross-section of a ring and a plurality of soft bearing pads of a downwind journal bearing assembly according to an example of the present disclosure; and

[0034] Figure 6 schematically illustrates a cross-section of a ring and a plurality of soft bearing pads of an upwind journal bearing assembly according to an example of the present disclosure.DETAILED DESCRIPTION OF EXAMPLES

[0035] 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.

[0036] 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 2, 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 space 111 defined inside the rotor hub 110. The space 111 may be defined as the hollow body of the rotor hub 110.

[0050] 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 may constitute a static front frame and the second structure may be attached to the generator rotor 31 and may also be called a rotating or rotatable shaft.

[0051] In figure 2, the front frame is an inner structure 13 and the rotating shaft is an outer structure 12. In another example, the front frame may be an outer structure and the rotating shaft 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.

[0052] The rotating shaft 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 t the rotor hub 110, the outer structure 12 and the generator rotor 31 together 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. The joint of this example 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 rotating shaft 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.

[0053] The front frame, e.g. the inner structure 13, may have a tapered region 18 towards the rotor hub 110. The rotating shaft, 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.

[0054] 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.

[0055] 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 component12 through the generator rotor 31. Conversely, if for example the second bearing component12 is braked, then the generator rotor 31 and the rotor hub 110 may be braked as well.

[0056] In an aspect of the present disclosure, a method 300 for repairing a journal bearing assembly of a wind turbine comprising a rotating component operatively connected to a wind turbine rotor and a static component supporting the static component is provided. Figure 3 shows a flow chart of the method 300.

[0057] The method 300 comprises, at step 302, selecting a first bearing pad to be removed.

[0058] The first bearing pad to be removed may be damaged. The method 300 for repairing a journal bearing assembly of a wind turbine may comprise a first step of identifying the damaged soft bearing pad. In some examples, selecting the first bearing pad may comprise visually inspecting one or more bearing pads through a clearance in a static component of the journal bearing. I.e. the rotor may be (slowly) rotated while the bearing pads mounted on the rotating component can be inspected one after the other as they move behind (or in front of) the clearance.

[0059] Additionally or alternatively, selecting the first soft bearing pad comprises analyzing signals indicating vibrations in the wind turbine e.g. a damaged pad may be identified using vibration signal monitoring. Such signals may be derived from a variety of sensors, which may include e.g. accelerometers in the frame, or on the tower, strain gauges on the rotor or frame or on the blades, current or voltage sensors in the generator or power converter and others.

[0060] In some examples, a damaged bearing pad may refer to a worn bearing pad i.e. a bearing pad that has degraded over time. During normal operation of the wind turbine, one or more of the soft bearing pads of the journal bearing assembly may suffer from wear, which may lead to a malfunction of the wind turbine. In other examples, a damaged bearing pad may refer to any other condition of the bearing pad caused while operating the wind turbine and which may lead to a malfunction of the whole journal bearing assembly.

[0061] Figure 4 schematically shows a cross-section of an example of a direct-drive wind turbine comprising a journal bearing assembly 18 according to an example of the present disclosure.

[0062] The journal bearing assembly 18 comprises a static component 17, a rotating component 12 operatively connected to the wind turbine rotor configured to rotate relative to the static component 17 and a ring 13 mounted on the static component 17.

[0063] 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 journalbearing assembly 18 may comprise a surface which may be configured to contact one or more bearing pads.

[0064] 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. In other examples, the ring 13 may be mechanically attached to the static component 17 e.g. using bolts.

[0065] In some examples the rotating component 12 may be a rotating shaft, rotatably mounted on and radially surrounding the static frame 11. The rotating shaft, in some examples, may drive the generator rotor.

[0066] The journal bearing assembly 18 further comprises a plurality of (relatively) soft bearing pads 15 mounted on the rotating component 12. The soft bearing pads 15 may be attached to the rotating component 12 e.g. using bolts. Journal bearings with a hard ring and relatively soft bearing pads are known in the art, and journal bearing assemblies which allow the repair of individual pads are known in the art. Contrary to prior art arrangement, the bearing pads in this configuration are mounted to the rotating component, whereas the harder ring is mounted on the static component.

[0067] The soft bearing pads may be located between the rotating component 12 and an outer surface 130 of the ring 13. The soft bearing pads 15 may be arranged in an annular way and may ensure rotation of the rotating component 12 relative to the static component 17, reducing the friction between them. The static component 17 and the rotating component 12 may exert pressure on the plurality of bearing pads 15 which may be clamped between these components. Accordingly, the bearing pads 15 may be able to withstand high loads.

[0068] In some examples, the soft bearing or sliding pads 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 pads may be wedge shaped.

[0069] In the present disclosure, the ring 13 is configured to provide a clearance between the ring 13 and the bearing pads in an area that is substantially unloaded by a weight of the wind turbine rotor. The clearance may define an exchange opening.

[0070] Different areas of the journal bearing assembly may be under different loads. The journal bearing assembly may comprise an upwind UW area and a downwind DW area. Further, the journal bearing assembly may comprise an upwind UW substantially unloaded area and a downwind DW substantially unloaded area.

[0071] The upwind UWarea of the journal bearing assembly may herein be interpreted as follows: when the wind turbine is operating normally, the nacelle and wind turbine rotor will besubstantially aligned with a prevailing wind direction. The wind will thus flow from an upwind side of the wind turbine to a downwind side of the wind turbine. The upwind UW area of the journal bearing assembly may be regarded as the area of the journal bearing assembly, which is located in the upwind side, i.e. in front of the tower. The downwind DW area of the journal bearing assembly may be regarded as the area of the journal bearing assembly which is located in the downwind side. Note that the downwind side of the journal bearing assembly does not need to be on the downwind side of the tower, and might be at the upwind side of the tower. The downwind journal bearing is however arranged more downwind than the upwind journal bearing. In other words, the upwind area may be located upstream of the downwind area relative to a wind flow direction. The terms “upwind” and “upstream” and the terms “downwind” and “downstream” may be used interchangeably.

[0072] Thus, the substantially unloaded area of the ring 13 may vary according to the location of the journal bearing assembly i.e. according to whether the ring 13 is in an upwind UW area of the journal bearing assembly or in a downwind DW area of the journal bearing assembly.

[0073] In some examples, the ring 13 may comprise an upwind UW substantially unloaded loaded area in a 6 o’clock position and a downwind DW substantially unloaded area in a 12 o’clock position. Figure 5 schematically shows an example of a cross-section of a ring 13 and a plurality of soft bearing pads 15 of a journal bearing assembly 18 according to an example of the present disclosure.

[0074] The ring 13 comprises a recess in the area that is substantially unloaded by the weight of the wind turbine rotor. I.e. the ring is not perfectly annular, but rather a portion of the ring is removed or flattened.

[0075] In particular, figure 5 illustrates a ring 13 located in a downwind DW area of a journal bearing assembly 18 of a wind turbine. The downwind DW journal bearing of the example comprises soft bearing pads 15, four of which are shown. The ring 13 comprises an outer surface 130 configured to contact one or more of the plurality of soft bearing pads 15.

[0076] In addition, the outer surface 130 of the ring 13 may comprise a recess 131 in the area that is substantially unloaded by the weight of the wind turbine rotor.

[0077] The recess 131 may be a cut-away section of the outer surface 130 of the ring and may define the clearance in the substantially unloaded area of the ring 13. During normal operation of the wind turbine, the bearing pads may still contact the ring attached to the static component in the areas with higher loads, ensuring a good functioning of the journal bearing assembly. Even though the recess of the ring is not optimal for operation, it has been foundto be acceptable because loads are significantly lower in that section, than elsewhere. I.e. the recess does not reduce the operational life of the wind turbine.

[0078] Further, the clearance may have at least a size of a soft bearing pad 15. A ring having a clearance with at least a size of the soft bearing pads may allow to access, remove and exchange a damaged soft bearing pad from the journal bearing assembly through the clearance. The soft bearing pads may be accessed by an operator from a side of the hub or from a side of the nacelle of the wind turbine through the clearance. In addition, as the clearance is located in the substantially unloaded area of the ring, the functioning of the journal bearing assembly during the wind turbine operation may not be negatively affected.

[0079] The outer surface 130 of the substantially unloaded area of the ring may also be a removable portion 132 or segment, and the clearance between the ring 13 and the bearing pads 15 may be defined by removing the removable portion 132 as may be further explained with reference to figure 6.

[0080] The method 300 for repairing a journal bearing assembly of a wind turbine comprises, after selecting a first soft bearing pad 151 to be removed, at step 304, positioning the first soft bearing pad 151 in a removal position, the removal position being in an area of the journal bearing assembly that is substantially unloaded by a weight of the wind turbine rotor.

[0081] Accordingly, figure 5 shows a first soft bearing pad 151 in a removal position according to an example of the present disclosure. Figure 5 schematically illustrates a crosssection of a ring 13 and a plurality of soft bearing pads 15 located in a downwind DW area of a journal bearing assembly.

[0082] In the figure, the first soft bearing pad 151 to be removed is positioned at an area of the journal bearing assembly that is substantially unloaded by the weight of the wind turbine rotor, i.e. substantially in a 12 o’clock position of the downwind DWjournal bearing assembly.

[0083] In the removal position, a pressure on the first bearing pad 151 may be released as the pad is not in contact with the ring 13 i.e. as it may be located such that its position matches the position of the recess of the ring. The pressure on the bearing pad may be released without the use of heavy lifting tools. In addition, unloading the soft bearing pad may allow further removal of the bearing pad through the clearance.

[0084] In further examples (not illustrated), positioning the first bearing pad 151 at an area of the downwind DWjournal bearing assembly that is substantially unloaded by the weight of the rotor may comprise positioning the bearing pad near a 12 o’clock position e.g. in a substantially 11 o’clock position or in a substantially 1 o’clock position. In yet further examples,the first bearing pad may be positioned in a substantially 10 o’clock position or in a substantially 2 o’clock position. In some examples, particularly when the removal position is a bit removed from the 12 o’clock position, a jack may be used to lift some of the weight of the rotor and help releasing the pressure of the bearing bad 151. The pressure of the bearing pad may be removed without lifting the entire weight of the rotor and therefore without the need of using heavy lifting tools. Figure 6 schematically illustrates a cross-section of a ring 13 and a plurality of soft bearing pads 15 located in an upwind UW area of a journal bearing assembly. Only four bearing pads 15 of the upwind UW journal bearing are shown in this example.

[0085] Figure 6 shows a first soft bearing pad 151 in a removal position according to another example of the present disclosure. The first soft bearing pad 151 is positioned at an area that is substantially unloaded by a weight of the wind turbine rotor, i.e. substantially in a 6 o’clock position of the upwind UW journal bearing assembly.

[0086] In the example of figure 6, the ring 13 comprises a removable portion 132 or segment in the area that is substantially unloaded by the weight of the wind turbine rotor, i.e. the outer surface 130 of the ring in an area that is substantially unloaded by the weight of the rotor is a removable portion 132. Thus, during normal operation of the wind turbine, the soft bearing pads 15 may be clamped between the removable portion 132 of the ring and the rotating component 12.

[0087] In some examples, the removable portion 132 may be removably attached to the rest of the ring 13. The removable portion 132 may be mechanically attached to the remainder of the ring 13, and a size of the removable portion 132 may correspond to a size of the exchange clearance.

[0088] In other examples, the removable portion 132 may be removably attached to the static component e.g., it may be bolted to the front frame.

[0089] In some examples, the removable portion 132 of the ring may be made of the same material as the remainder of the ring 13. In some examples, the removable portion 132 of the ring 13 may be made of steel.

[0090] As figure 6 represents an upwind UW journal bearing of a configuration substantially corresponding to figure 4, the substantially unloaded area of the ring is located substantially in 6 o’clock position. However, in other examples, the removable portion 132 of the ring may be located at a downwind DW journal bearing, and the substantially unloaded area of the ring may be substantially in a 12 o’clock position. In other wind turbine configurations, the areas which are substantially unloaded by the weight of the wind turbine may be otherwise arranged e.g. depending on whether the wind turbine is an upwind or downwind wind turbine, depending on how the rotating component is supported and others.

[0091] In further examples (not illustrated), positioning the first bearing pad 151 at an area of the upwind UW journal bearing assembly that is substantially unloaded by the weight of the rotor may comprise positioning the bearing pad near a 6 o’clock position e.g. in a substantially 5 o’clock position or in a substantially 7 o’clock position. In yet further examples, the first bearing pad may be positioned in a substantially 4 o’clock position or in a substantially 8 o’clock position. In some examples, particularly when the removal position is a bit removed from the 6 o’clock position, a jack may be used to lift some of the weight of the rotor and help releasing the pressure of the bearing bad 151. The pressure of the bearing pad may be removed without lifting the entire weight of the rotor and therefore without the need of using heavy lifting tools.

[0092] Once the first bearing pad 151 is in the removal position, the method 300 comprises, at step 306, locking the rotating component and maintaining the first soft bearing pad 151 in the removal position.

[0093] In some examples, locking the rotating component may comprise mechanically locking the rotating component. In some examples, mechanically locking the rotating component may comprise inserting a pin in a hole of a locking plate operatively connected to the wind turbine rotor. 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.

[0094] The method further comprises, at step 308, removing the first soft bearing pad through a clearance created in the ring mounted on the static component.

[0095] The present method provides a way of removing a soft bearing pad from a journal bearing assembly uptower without the use of lifting tools, that is, without the need of lifting the entire weight of the rotor to create the necessary space to access and remove the soft bearing pads. Rather, in the present method the weight of the rotor does not have to be lifted and is advantageously used as support. A correct functioning of the journal bearing assembly may then be ensured in a more efficient and cost-effective manner.

[0096] In some examples, removing the first soft bearing pad 151 may comprise detaching the first soft bearing pad 151 from the rotating component 12 and removing the pad 151 through the clearance. The pad 151 may be removed from a hub side of the wind turbine and / or from a side of the nacelle. In some examples, the soft bearing pad may be removed through the clearance from an upwind side of the wind turbine.

[0097] In some examples, the ring mounted on the static component comprises a recess creating a clearance. In these examples, removing the first bearing pad 151 through theclearance may comprise removing the first bearing pad through the recess 131 in an area of the ring 13 which is substantially unloaded by a weight of the wind turbine rotor.

[0098] In other examples, the method may comprise removing a removable portion 132 of the ring and creating the clearance in the substantially unloaded area of the ring 13 prior to removing the first bearing pad. The pressure on the first bearing pad 151 may be released as the pad may no longer contact the outer surface of the least loaded area of the ring 13. The clearance may further allow access to the soft bearing pad.

[0099] In some examples, the removable portion 132 may be detached from the remainder of the ring 13 by unscrewing multiple bolts.

[0100] In some examples, the method may further comprise introducing a second soft bearing pad through the clearance and attaching the second soft bearing pad to the rotating component 12.

[0101] In some examples, the method may further comprise reattaching the removable portion 132 of the ring to the remainder of the ring or to the static component.

[0102] In a further aspect of the present disclosure, a wind turbine is provided. The wind turbine comprises a wind turbine rotor including a hub 110 and a plurality of blades, a rotating shaft 12 operatively connected to the wind turbine rotor, a static frame 17 supporting the rotating shaft 12 and an upwind UW journal bearing assembly and a downwind DW journal bearing assembly including a ring 13 mounted on the static frame 17, and a plurality of bearing pads 15 on the rotating shaft 12.

[0103] The rotating shaft 12 radially surrounds the static frame 17, and the ring 13 of the upwind UW journal bearing assembly is configured to provide a clearance between the ring 13 and the bearing pads 15 substantially in a 6 o’clock position and / or the ring 13 of the downwind DW journal bearing assembly configured to provide a clearance between the ring 13 and the bearing pads 15 substantially in a 12 o’clock position.

[0104] In some examples, the clearance of the upwind journal bearing assembly and / or the clearance of the downwind bearing assembly may be sufficiently larger than a height of the bearing pads for removal of a bearing pad.

[0105] In some examples, the ring of the upwind journal bearing assembly and / or the ring of the downwind journal bearing assembly may comprise a cut-out. In other examples, the ring of the upwind journal bearing assembly and / or the ring of the downwind journal bearing assembly may comprise a removable ring segment.

[0106] In some examples, the inner ring 13 may be shrunk fit on the frame 17. In other examples, the inner ring 13 may be mechanically attached to the frame 17 e.g. using bolts.

[0107] In some examples, the rotatable shaft 12 may be directly coupled to a rotor of a generator 31.

[0108] 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 as other 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 of a wind turbine comprising a rotating component operatively connected to a wind turbine rotor, and a static component supporting the rotating component, and the method comprising: selecting (302) a first bearing pad to be removed, the first bearing pad being mounted on the rotatable component; positioning (304) the first bearing pad in a removal position, the removal position being in an area of the journal bearing assembly that is substantially unloaded by a weight of the wind turbine rotor; locking (306) the rotating component and maintaining the first bearing pad in the removal position; and removing (308) the first bearing pad through a clearance created in a ring mounted on the static component.

2. The method (300) of claim 1 , wherein removing the first bearing pad comprises detaching the first bearing pad (151) from the rotating component (12) and removing the bearing pad (151) through the clearance.

3. The method (300) of claims 1 or 2, wherein the ring (13) mounted on the static component (17) comprises a recess (131) creating the clearance.

4. The method (300) of claims 1 or 2, comprising removing a removable portion (132) of the ring (13) to create the clearance prior to removing the first bearing pad (151).

5. The method of any of claims 1 - 4, further comprising introducing a second bearing pad through the clearance and attaching the second bearing pad to the rotating component (12).

6. The method (300) of any of claims 1 - 5, wherein selecting the first bearing pad (151) comprises visually inspecting one or more bearing pads (15) through the clearance.

7. A journal bearing assembly (18) of a wind turbine, comprising: a static component (17); a rotating component (12) operatively connected to a wind turbine rotor, configured to rotate relative to the static component (17); a ring (13) mounted on the static component (17); and a plurality of bearing pads (15) mounted on the rotating component (12), whereinthe ring (13) is configured to provide a clearance between the ring (13) and the bearing pads (15) in an area that is substantially unloaded by a weight of the wind turbine rotor.

8. The journal bearing assembly (18) of claim 7, wherein the ring (13) comprises a removable portion in the area that is substantially unloaded by the weight of the wind turbine rotor.

9. The journal bearing assembly (18) of claim 7 or 8, wherein the removable portion is removably attached to the ring (13).

10. The journal bearing assembly (18) of claim 7 or 8, wherein the removable portion is removably attached to the static component.

11. The journal bearing assembly (18) of any of claims 7 - 9, wherein the ring (13) comprises a recess (131) in the area that is substantially unloaded by the weight of the wind turbine rotor.

12. The journal bearing assembly (18) of any of claims 7 - 10, wherein the rotating component (12) is a rotatable shaft connected to a hub (110) of the wind turbine rotor, and the static component (17) is a front frame (11) supporting the rotatable shaft.

13. A wind turbine (10) comprising a wind turbine rotor (18) including a hub and a plurality of blades; a rotating shaft operatively connected to the wind turbine rotor; a static frame supporting the rotating shaft; and an upwind journal bearing assembly according to any of claims 7 - 11 and a downwind journal bearing assembly according to any of claims 7 - 11 including a ring mounted on the static frame, and a plurality of bearing pads on the rotating shaft, wherein the rotating shaft radially surrounds the static frame, and wherein the ring of the upwind journal bearing assembly is configured to provide a clearance between the ring and the bearing pads substantially in a 6 o’clock position and / or the ring of the downwind journal bearing assembly is configured to provide a clearance between the ring and the bearing pads substantially in a 12 o’clock position.

14. The wind turbine of claim 13, wherein the clearance of the upwind journal bearing assembly and / or the clearance of the downwind bearing assembly is sufficiently large for removal of a bearing pad.

Images