EP4426940A1

EP4426940A1 - Yaw ring for wind turbine

Info

Publication number: EP4426940A1
Application number: EP22800083.2A
Authority: EP
Inventors: Nicolaj Biltoft KRISTENSEN
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2021-11-01
Filing date: 2022-10-20
Publication date: 2024-09-11
Also published as: WO2023072353A1

Abstract

A yaw ring assembly for a wind turbine. The yaw ring assembly comprises a plurality of yaw ring members which fit together to form the yaw ring assembly, wherein the yaw ring members are configured to interlock with mutually adjacent yaw ring members. A benefit of the invention is that since the yaw ring members are configured to interlock with one another, this avoids the need to use separate joining components such as plates or bolts to couple the individual yaw ring segments together. The invention extends to a method for manufacturing a yaw ring assembly, comprising: forming a plurality of yaw ring segments; fitting the plurality of yaw ring segments together to define a completed yaw ring assembly. The step of fitting the plurality of yaw ring segments together comprises interlocking at least some of the yaw ring members with compatibly interlocking adjacent yaw ring members.

Description

YAW RING FOR WIND TURBINE

Technical Field

The invention relates to a configuration of a yaw ring or bearing for a wind turbine, a method of manufacturing, and also to a method of replacement and/or installation of such a yaw ring.

Background to the Invention

A common configuration of wind turbine is the so-called horizontal axis wind turbine, or HAWT. In such a wind turbine, a nacelle is supported on top of a tower. The nacelle houses the power generation equipment for the wind turbine and is coupled to a rotatably supported rotor, usually having three blades.

Since wind flow can come from different directions, a wind turbine nacelle is typically connected to its tower by a yaw system. That yaw system comprises a bearing located between the top of the tower and a suitable support structure of the nacelle. A yaw system further comprises a drive system which is configured to rotate the nacelle on the yaw bearing with respect to the tower.

Driven by the overall cost of energy, wind turbines are becoming every larger. It is now known for offshore wind turbines to exceed 10MW generation capacity. This means that towers are getting taller and larger in diameter, and nacelles and rotors are becoming larger and heavier. These factors drive up the size and weight of the yaw system. For example, it is known for yaw bearings to have a diameter in excess of 5m, corresponding to the diameter of the flange at the top of the tower. This means that yaw bearing are very heavy components which makes them challenging to work on after installation. Further, since yaw bearings are sandwiched between the nacelle and the tower top flange, the nacelle must be removed for the bearing to be replaced. Typically, this will require a crane, but this is not desirable for increased tower top heights, and particularly in offshore locations where a floating vessel would also be required. It is an object of the present invention to provide a solution to one or more of the problems mentioned above.

Summary of the Invention

According to a first aspect of the invention, there is provided a yaw ring assembly for a wind turbine. The yaw ring assembly comprises a plurality of yaw ring members which fit together to form the yaw ring assembly, wherein at least some of the yaw ring members are configured to interlock with mutually adjacent yaw ring members.

A benefit of the invention is that since the yaw ring members are configured to interlock with one another, this avoids the need to use separate joining components such as plates to couple the individual yaw ring segments together.

The yaw ring assembly may define a radially outward gear surface which may be toothed. In other examples, a toothed gear surface may be defined on a radially inward surface of the yaw ring assembly.

Each interlocking yaw ring member may comprise a first interlocking portion and a second interlocking portion, wherein each of the first and second interlocking portions interlocks with a different yaw ring member of the yaw ring assembly. Those interlocking portions may extend in the circumferential direction. The yaw ring members can therefore be considered as being placed side-by-side in the circumferential direction.

The first interlocking portion may be shaped to define a wedge and wherein the second interlock portion is shaped to define a recess, wherein the wedge and the recess are complimentary shaped to lock together in the circumferential direction. In one example the wedge and the recess shape of the respective interlock portions extends completely through the radial thickness of the yaw ring segments. This feature means that yaw ring segments can be removed from the yaw ring assembly in a radial direction, in the manner of removing a slice from a circular shape.

The wedge and the recess may have complimentary trapezoidal profiles. In other examples, those profiles may be generally conical. In other examples, the wedge may have at least a first circumferential wedge surface which is engageable with a respective first circumferential recess surface defined by the recess. Those wedge and recess surfaces may be inclined with respect to a yaw ring access which has the effect of applying tension between neighbouring yaw ring segments.

The invention extends to a method for manufacturing a yaw ring assembly. The method comprises providing a yaw ring; separating the yaw ring into a plurality of yaw ring segments; and, fitting the plurality of yaw ring segments together to define a completed yaw ring assembly. Fitting the plurality of yaw ring segments together comprises interlocking at least some of the yaw ring members with compatibly interlocking adjacent yaw ring members.

When the yaw ring members are fitted together, the yaw ring assembly may define a radially-facing surface on which may be formed a gear formation. The radially-facing surface may face radially inward or outward.

In order for the gear formation to be formed most precisely, the gear formation may be formed on the radially-facing surface of the yaw ring assembly before the yaw ring is separated into a plurality of segments.

When the yaw ring assembly is being assembled onto a wind turbine tower, it is useful for technicians to be able to identify the order in which the yaw ring segments should be assembled. To this end, each of the yaw ring segments may be appropriately marked with an identification marker indicative of the respective ordering of the yaw ring segments in the yaw ring assembly.

Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to the attached drawings, in which:

Figure 1 is a schematic view in cross section of a wind turbine tower connected to a nacelle by a yaw system; Figure 2 is a view from above of a yaw ring of the yaw system in Figure 1 , in accordance with an example of the invention;

Figure 3a is a circumferential cross section through a portion of the yaw ring shown in Figure 2, together with a plan view of that portion, which shows more clearly how neighbouring yaw segments of the yaw ring interlock together, whereas Figure 3b shows an alternative example of a circumferential cross section of the yaw ring;

Figures 4a-c show different examples of how two neighbouring yaw ring segments may be interlocked;

Figure 5 shows a sequence of steps indicating how a yaw ring assembly may be manufactured; and

Figure 6 shows another sequence of manufacturing steps, similar to those shown in Figure 5.

Detailed Description

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

With reference to Figure 1 , a wind turbine 2 includes a tower 4 and a nacelle 6 mounted on top of the tower 4. It should be noted that Figure 1 is schematic in form and that the tower 4 is shown only partially so as not to obscure the invention. Consequently, other features of the tower 4 that may usually be present such as access structures, power cables, lightning protection systems and so on have not been shown for brevity.

The nacelle 6 is mounted to the tower 4 by way of a yaw system 8. The yaw system 8 includes a yaw ring 10 that is situated between the nacelle 6 and the tower 4 and allows the nacelle 6 to rotate with respect to the tower 4. As shown here, the yaw ring 10 is a single part which sits between the tower 4 and the nacelle 6 and provides a slide bearing formation, as is known in the art. Conventionally slide bearing are used as yaw bearings because they are well-suited to cope with the high loads that are generated from the mass of the nacelle. It should be appreciated, however, that other forms of bearings, such as roller bearing are not intended to be excluded from the invention, as defined by the claims.

In the illustrated embodiment the nacelle includes a base frame 18 which is slidingly coupled to the yaw ring 10. Yaw claws 20 may be provided for this purpose which, as is known, constrain axial movement of the base frame 18 but allow the base frame 18 to rotate angularly about the tower axis A. The base frame 18 can be any structure that is suitable to transfer the load of the nacelle 6 to the tower 4 via the yaw ring 10. Typically, the base frame 18 is connected directly or indirectly to the main bearings of the nacelle 6, as well as to the supporting structure for the outer walls of the nacelle.

The yaw ring 10 is fixed to an upper flange of the tower 4, which will hereinafter be referred to as a top tower flange 22. The fixing may be achieved by any suitable means, which is typically a circular array of bolts 23.

The yaw ring 10 defines a gear surface 24 which faces radially outwards in the illustrated embodiment, with respect to the tower axis A. Note that in some arrangements this configuration may be reversed such that the gear surface faces radially inwards.

The yaw system 8 further comprises a yaw drive 26. The yaw drive 26 includes a yaw gear 28 that is engaged with the gear surface 24 of the yaw ring 10. As shown, the yaw drive 26 is associated with the nacelle 6. Therefore, operation of the yaw drive 26 turns the nacelle 6 with respect to the tower 4.

Conventionally, the yaw ring 10 is formed of a single part of machined steel due to the high forces the yaw ring 10 must tolerate during use. However, the drawback of such a design is that yaw rings become increasingly large and heavy as the overall size of wind turbines increase. This makes yaw rings challenging to install, maintain and replace. The invention addresses this issue. As shown in Figures 2 and 3, the yaw ring 10 is constituted by a yaw ring assembly 30 comprising a plurality of yaw ring members 32. The yaw ring members 32 are configured to interlock with mutually adjacent ones of the yaw ring members 32.

The yaw ring assembly 30 may be comprised of any number of yaw ring members 32. In general, however, the number of yaw ring members 32 may be influenced by the portability required from them. For example, smaller yaw ring members 32 may be carried by hand, although including too many yaw ring members in a yaw ring assembly may prove more complicate manufacture and assembly. Each yaw ring member 32 may be of equal size, but this is not essential. Notably, each yaw ring member 32 would have substantially identical cross section along their length. However, the circumferential span of the yaw ring members may differ. It is envisaged that in practice at least four yaw ring members 32 would be a practical number to ensure portability. For lifting by hand, a limit of around 50kg to 70kg is to be expected so this would mean a larger number of yaw ring members would be required for larger and heavier yaw ring assemblies.

Figure 2 demonstrates an example where the yaw ring members 32 are different sizes. Here, it will be noted that there is one large yaw ring member, shown as 32a, and a series of smaller yaw ring members which are shown here as 32b-32i. It should be noted however that this is only exemplary and should not be considered limited. Moreover, other arrangements are acceptable. In a preferred arrangement, the yaw ring members are the same size.

Each of the yaw ring members 32 fit together in an interlocking manner to form the completed yaw ring 10, which is shown here as defining the radially outward facing gear surface 24. An inward facing gear surface would also be possible, however.

Interlocking of the yaw ring members 32 with their adjacent neighbours provides various advantages. One benefit of the interlocking configuration is that the yaw ring members 32 are made to fit together without the use of external components such as fixing plates. A further benefit is that the interlocking formations between adjacent yaw ring members 32 can be configured to ensure that tension is applied to the assembly which improves its stiffness and avoids ovalization/misshaping during use. Figures 3a and 3b illustrate variants of the interlocking configuration in more detail. In Figure 3a, the lower view shows a view from above of the yaw ring assembly of Figure 2, focussing on two neighbouring yaw ring segments, which are labelled here as 32a and 32b, whereas the upper view shows a cross section through the line A-A. As can be seen the two yaw ring members 32a, b interlock at an interlock region 40. In this region, a first interlocking portion 42 of the first yaw ring member 32a overlaps and interlocks with a second interlocking portion 44 of the second yaw ring member 32b. As can be seen, the interlocking portions 42,44 extend in the circumferential direction. It will be appreciated that each yaw ring member will include a first interlocking portion and a second interlocking portion.

The first interlocking portion 42 of the first yaw ring member 32a includes interlocking elements which, in the illustrated embodiment, comprise a recess 46 and a projection, wedge, lug or lobe 48. Similarly, the second interlocking portion 44 of the second yaw ring member 32b includes interlocking elements, which in the illustrated example comprise a recess 50 and a projection, wedge, lug or lobe 52.

The first interlocking portion 42 is shaped in a complementary way to mate with the second interlocking portion 44. As such, the lug 48 of the first interlocking portion 42 fits into the recess 50 of the second interlocking portion 44. Correspondingly, the lug 52 of the second interlocking portion 44 fits into the recess 46 of the first interlocking portion 42.

In this example, it should be appreciated that the cross section shown in the upper view of Figure 3a is uniform throughout the yaw ring members 32a, b. Therefore, the recesses 46,50 and the lugs 48,52 extend across the full radial width of the yaw ring members 32a, b. This is an advantage in terms of assembly because the yaw ring segments 32 can be slid against one another in the radial direction, allowing easy placement of a yaw ring segment against other segments.

As can be seen in Figure 3a, the lugs 48,52 and the recesses 46,50 are defined by a series of wall sections. In the orientation of the drawings, the wall sections are perpendicular to one another in this example. Referring to the yaw ring member 32a on the left hand side of the figure, the first interlocking portion 42 comprises wall sections 54a-e, the geometry of which define the recess 46 and the lug 48. Wall sections 54a, 54c and 54e are vertical, in the orientation of the drawing and so are aligned with a rotational axis of the yaw ring assembly 30. Moreover, in view of the way in which the individual yaw ring members 32 are separated, each of the vertical wall sections 54a, c,e can be considered to be in radial planes that pass through the yaw ring axis.

Although the interlocking portions 42,44 provide a useful means of coupling neighbouring yaw ring members 32,32b together, an optional yet preferred feature is to provide a supplementary means to fix the yaw ring members 32a, 32b to each other. This may be achieved by suitable mechanical fasteners such as bolts 59. As shown in Figure 3a, the bolts 59 extend through the lug 48 of the first yaw ring member 32a and the recess 50 of the second yaw ring member 32b. Other positions would be acceptable, however, within the principle of mechanically fixing the first yaw ring member 32a to the second yaw ring member 32b.

Figure 3b shows another example of interlocking yaw ring members 32a, 32b. In this example, the lug 52 of the second yaw ring member 32b is provided with a trapezoidal profile in cross section. As such, the lug 52 has opposed shoulders 60,62 that are inclined to the yaw ring axis. Correspondingly, the recess 46 of the first yaw ring member 32a is shaped to have a trapezoidal profile in cross section. The benefit of the trapezoidal profiles of the recess 46 and the corresponding lug 52 is that the inclined shoulders 60,62 serve to place the neighbouring yaw ring members 32a, b in tension which reduces the likelihood of ovality occurring in the yaw ring assembly 30 in the assembled configuration

It should be noted in this respect that although the above examples show lugs 48,52 having trapezoidal profiles such that there are two opposed inclined surfaces, this is not essential. It is envisaged, therefore, that only one of the cooperating lug surfaces and recess surfaces may be inclined in the circumferential direction, with respect to the yaw axis, as this will provide the required tensioning effect between neighbouring ones of the yaw ring segments.

Further examples of interlocking configurations of yaw ring members are shown in Figures 4a-4c. Figure 4a is a circumferential cross section view like that in Figures 3a and 3b. However, in these examples, the wall sections of the interlocking portions do not extend the full radial width of the respective yaw ring members 32a, 32b. Instead, the interlocking portions 42,44 comprise discrete interlocking features that are located between the radially inner and outer surfaces of the yaw ring 10.

One example of this is shown in Figure 4b where the lugs 48,52 are pyramidal in shape and fit into pyramid-shaped concave recesses 46,50.

Another example is shown in Figure 4c, wherein the lugs 48,52 are frustoconical in shape and fit into frustoconical-shaped concave recesses 46,50.

Having described the configuration of some examples of a segmented yaw ring assembly 30, the discussion will now focus on a method by which a yaw ring assembly as discussed with reference to the illustrated examples may be manufactured.

With reference to Figure 5, a yaw ring assembly 30 in accordance with the invention may be manufactured by way of a multi-step process which starts with the provision of a yaw ring 10. The yaw ring may be constituted from high strength steel suitable for a high load application, as would be understood by a skilled person. Preferably a suitable type of steel is of a grade appropriate to be induction hardened, for example medium-carbon steels (e.g. 0.3 to 0.5% carbon) with or without alloying components.

In step 100, the yaw ring can be considered to be a ‘blank’ as it does not yet carry gear teeth. Therefore, in step 102, the yaw ring 10 is processed to provide gear teeth 103 on a radial-facing surface. Here, the gear teeth are being formed on a radially outward facing surface, although inward facing gear teeth would also be acceptable.

The gear teeth 103 may be formed by any suitable technique as would be known in the art, such as an appropriate machining process.

Once the gear teeth 103 are formed on the yaw ring 10, at step 104 the yaw ring 10 is divided into yaw ring segments 32 to provide a yaw ring assembly 30. As discussed above the yaw ring members 32 may be formed to provide interlocking formations on circumferential ends thereof. Once the yaw ring 10 has been cut up into individual yaw ring segments 32, those segments can be stored until they are needed, for example when it is required to replace a worn or damaged yaw ring on a wind turbine tower.

It will be appreciated that since the yaw ring segments are cut from a single piece yaw ring, they will be able to fit together precisely to form a complete yaw ring with an accurately machined gear surface.

In order that the yaw ring segments 32 can be assembled correctly into a completed yaw ring, appropriate identifying markings can be provided on the yaw ring segments 32 to indicate the order in which they should be assembled. The markings may take any appropriate form. For example, the markings may be a series of ordinal number stamps, painted or otherwise applied to each yaw ring successively. Another option is an appropriate bar code or QR code which can be read by an appropriate code reader so as to gather certain useful information such as the assembly order of the yaw ring segment in question place of manufacture, yaw ring diameter, gear pitch and so on. The appropriate markings can be formed on a pre-assembled yaw ring before it is assembled on a wind turbine.

In the final step, step 106, the individual yaw ring segments 32 are assembled onto the top of a wind turbine tower 4. The yaw ring assembly 30 is shown in its assembled position in dashed lines.

Various approaches may be taken to assemble the yaw ring assembly 30 on top of the tower 4. In one example, all of the yaw ring segments 32 can be placed into their predetermined locations and interlocked with one another. Once the yaw ring assembly 30 is in place on the tower, then appropriate fasteners such as bolts can be applied to secure the yaw ring assembly 30 to the tower 4.

In another example, a starting segment can be applied to the tower 4 as an initial step and connected to the tower using e.g. bolts, as is common in the art. The starting segment therefore acts as a datum piece from which the rest of the yaw ring assembly 30 can be assembled. Each segment can therefore be added to the assembly in a piece-by-piece basis until the entire yaw ring assembly has been completed. The individual segments can be bolted down at an appropriate time, which may be when the yaw ring assembly is completed. Alternatively, each segment can be bolted down one it has been placed in position.

Figure 6 shows another method of manufacture of a yaw ring assembly 30 in accordance with the invention. In contrast to the method described above with reference to Figure 5, in this alternative method the yaw ring assembly 30 is formed by separate yaw ring members 32 at the outset, as illustrated at step 200. Here, the yaw ring assembly 30 is shown as comprising four yaw ring members 32, by way of example.

Each of the yaw ring members 32 is therefore formed separately before being connected to form the yaw ring assembly 30. This may be achieved by casting each yaw ring member 32 by an appropriate casting method, for example sand casting. As an alternative approach, each yaw ring member 32 may be cut from a piece of sheet material 201 , for example a large steel sheet. The steel sheet may be constituted from high strength steel suitable for a high load application, as would be understood by a skilled person. Preferably a suitable type of steel is of a grade appropriate to be induction hardened, for example medium-carbon steels (e.g. 0.3 to 0.5% carbon) with or without alloying components

It is envisaged that once each yaw ring member 32 is cut from the sheet 201 , the members 32 would be processed appropriately with interlocking elements as discussed above for interlocking with adjacent yaw ring segments, and also have formed therein suitable bores for receiving coupling bolts. This can be achieved using suitable milling and drilling/boring processes. It is anticipated that the yaw ring member 32 may be between 100mm and 150mm in thickness by way of example only. In the case of the yaw ring members being cut from a sheet 201 , the thickness dimension is taken to be the planar thickness of the sheet.

Following the formation of the individual yaw ring members 32, they are assembled together to form a complete yaw ring assembly, as shown at step 202. At this point, appropriate surface finishing such as grinding and polishing processes can be performed in order to create a smooth bearing surface, as required. At this point the yaw ring assembly 30 can also be processed appropriately to form its gear surface 64. In principle, the gear surface could be applied by an additive manufacturing process, but it is envisaged most likely that a subtractive process such as milling would be most appropriate to maximise strength. One the yaw ring assembly 30 has been fully formed, it can be appropriately marked so that the order of assembly can be followed later. Since the gear surface 64 has been formed on the assembly yaw ring, it is important that the separate yaw ring members 32 are assembled in the correct order. Therefore, at step 204 the yaw ring members 32 are marked appropriately with identifying marks that indicate the assembly sequence, as is shown here by way of example. At this stage, in the event that a spare yaw ring is required in the future, a suitable three — dimensional scan of the fully assembled yaw ring assembly can be performed so that an identical yaw ring may be manufactured at a later date when needed.

The yaw ring assembly 30 can then be disassembled and stored ready for use. Finally, at step 206 the yaw ring assembly 30 is assembled in situ, as discussed above at step 106 with reference to Figure 5

The skilled person would appreciate that various modifications may be made to the examples of the invention shown and described here without departing from the inventive concept as defined by the claims

Claims

1 . A yaw ring assembly (30) for a wind turbine, comprising: a plurality of yaw ring members (32) which fit together to form the yaw ring assembly (30), wherein the yaw ring members are configured to interlock with mutually adjacent yaw ring members.

2. The yaw ring assembly of Claim 1 , wherein the yaw ring assembly (30) defines a radially-facing gear surface (34).

3. The yaw ring assembly of Claims 1 or 2, wherein each yaw ring member (32) comprises a first interlocking portion (42) and a second interlocking portion (44), wherein each of the first and second interlocking portions interlocks with anotheraw ring member of the yaw ring assembly.

4. The yaw ring assembly of Claim 3, wherein at least one and preferably both of the first and second interlocking portions (42,44) extend in a circumferential direction.

5. The yaw ring assembly of Claim 4, wherein the first interlocking portion (42) of a first one of the yaw ring members overlaps with the second interlocking portion (44) of a second one of the yaw ring members in an interlock region (40).

6. The yaw ring assembly of Claim 5, wherein the first interlocking portion (42) is shaped to define a wedge (48) and wherein the second interlock portion is shaped to define a recess (50), wherein the wedge and the recess are complimentary shaped to lock together in the circumferential direction.

7. The yaw ring assembly of Claim 5 wherein the wedge and the recess have complimentary trapezoidal profiles.

8. The yaw ring assembly of Claim 5, wherein the wedge and the recess have complimentary conical profiles.

9. The yaw ring assembly of Claim 6, wherein the wedge (48) has first and second wedge surfaces which are engageable with first and second recess surfaces defined by the recess (50), wherein at least one of the wedge surfaces and a corresponding one of the corresponding recess surfaces are inclined with respect to a yaw ring axis.

10. The yaw ring assembly of Claim 9, wherein the wedge has first and second wedge surfaces which are engageable with first and second recess surfaces of the recess, and wherein both of the wedge surfaces and corresponding ones of the corresponding recess surfaces are inclined with respect to a yaw ring axis.

11 . The yaw ring assembly of any one of the preceding claims, comprising at least four yaw ring segments (32).

12. A method for manufacturing a yaw ring assembly, comprising: forming (104,200) a plurality of yaw ring segments; fitting (106,206) the plurality of yaw ring segments together to define a completed yaw ring assembly; wherein fitting the plurality of yaw ring segments together comprises interlocking at least some of the yaw ring members with compatibly interlocking adjacent yaw ring members.

13. The method of Claim 12, wherein, when the yaw ring members are fitted together, the yaw ring assembly defines a radially-facing surface, and wherein the method further comprises: forming (102,202) a gear formation on the radially-facing surface.

14. The method of Claim 12 or 13, wherein the step of forming (104) a plurality of yaw ring segments further comprises: providing (100) a yaw ring, and separating (104) the yaw ring into the plurality of yaw ring segments.

15. The method of Claim 14, when dependent on Claim 12, wherein, before separating the yaw ring into a plurality of yaw ring segments, the method further comprises: forming a gear formation on the radially-facing surface.

16. The method of Claim 13 or Claim 15, wherein the gear formation is formed on a radially outward facing surface.

17. The method of any of Claims 12 to 16, further comprising marking each of the yaw ring segments with identifying markers indicative of the respective ordering of the yaw ring segments in the yaw ring assembly.

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