HK1135163B - Assembly notably for a wind turbine having stress transfer on bearings - Google Patents

Description

Device for a wind turbine for transferring stresses to a bearing

This application is a divisional application of patent application No. 200610137129.2 filed on 4.7.2006.

Technical Field

The present invention relates to a device for a wind turbine, in particular a pivot bearing for a servo drive for a blade on a rotor head of said wind turbine.

Background

Document EP- ｃA-1266137 describes ｃA device comprising ｃA bearing between the rotor head and such ｃA wind turbine blade. The device specifically comprises:

-a first bearing ring and a second bearing ring having different diameters radial parallel to the blade axis,

a connection portion integrated into or embedded in the rotor hub, interposed between the blade and the bearing ring and extending in a radial direction with respect to the blade axis with respect to said first and second bearing rings to which it is connected,

-a third bearing ring arranged in a radial direction with respect to the blade axis between the first and second bearing rings, the third bearing ring being connected to the rotor head, at least one of the connecting portion, the first or second bearing ring being connected to the blade.

In particular, in the above-mentioned wind turbines, the bearing ring is subjected to great stresses. The blades are subjected not only to significant stresses along the respective blade axis (axial stresses) but also to considerable stresses exerted in a radial direction with respect to the blade and rotor hub axis (radial or centrifugal stresses).

Bearing strength is required to be increased by factors such as rotational speed, increasing wind turbine size, wind induced stresses and blade angle dependent stresses.

With respect to the aforementioned blade angle, the blade is typically capable of rotating about its elongate axis about 10 degrees depending on the wind direction to improve efficiency.

The bearing rings arranged for the roller bearings, the connections between the bearing rings, the rotor head and the blades are the main elements in the operation of the wind turbine.

The object of the invention described herein is to remedy the above-mentioned deficiencies of the prior art solutions by increasing the mechanical strength of the bearing, improving the running conditions of the connection and reducing the costs.

Disclosure of Invention

In the proposed solution, the aforementioned means comprise a blade, a bearing and a rotor head, said connection or joint extending parallel to a radial direction with respect to the axis of the blade, the first and second bearings being connected to said joint in front of said first and second bearings by first and second fixing means, respectively.

In an alternative or another solution to the above problem, other devices with a pivot bearing between a first element (or unit) and a second element (or unit) intended for use in wind turbines or other large engines (cranes) have also been considered. In this known arrangement the aforementioned attachment portion is replaced by a (separate) attachment member interposed between the second member and the first and second bearing rings and extending in a radial direction relative to the axis of the second member relative to (or in front of) the first and second bearing rings to which it is attached.

In order to be able to solve at least some of the same problems associated with high stress conditions, it is proposed according to an aspect of the invention that at least one of the first and second bearing rings is connected to a (separate) connecting element instead of (not directly) to the second element, but is connected to the second element via said connecting element.

Thus, the second elements (blades) will only be connected to the third bearing ring (middle part) and will therefore not be directly connected to the first and second outer rings.

Although the two solutions have different technical features, corresponding respectively to the connection portion and to the (separate) connection element, they are able to solve the problems already explained above: the strength under stress of bearings in wind turbines of increasing power, which are operated under conditions of increasing mechanical stress, is increased, in particular in a radial direction with respect to the axis of rotation of the/each blade.

On the second element/blade side (via the connecting element) or the first element/rotor head side (via the connecting portion or connecting section), they are indirectly connected by means of the first and second bearing rings to form a system, which is generally subjected to at least one aspect of stress for both bearing rings.

In the second case, the applicant recommends:

the third bearing ring is connected to the blade by a third connection (directly),

the first and second connecting pieces are arranged together on the connecting portion in correspondence with the first and second bearing rings, respectively, with a radial spacing with respect to the blade axis that is different from the spacing between the third connecting piece and the blade axis.

Advantageously, the rotor head comprises a first bearing ring and a second bearing ring, the first bearing ring being arranged to be coupled to the first bearing ring and the second bearing ring being arranged to be coupled to the second bearing ring, the second bearing ring being arranged to be coupled to the second bearing ring.

If a solution using a connecting element on one side of the blade is preferred, the applicant recommends:

in one radial plane with respect to the blade axis, the first and second bearing rings are connected to the blade by a single connection, such that (all) stresses exerted on the first and second bearing rings simultaneously pass through the single connection, which is not dedicated to either of the bearing rings,

and/or, in a radial plane with respect to the axis of the blade, each of the first and second bearing rings is connected directly to the connecting element and not to the blade, the individual connecting elements also being connected to the blade by a single connecting piece, so that (all) the stresses exerted on the first and second bearing rings at the same time pass through said individual connecting pieces,

and/or the first bearing ring, which is radially furthest from the blade axis, is directly connected to the connecting element, instead of to the blade, the second bearing ring (in a radial plane with respect to the blade axis) being connected to said connecting portion and to said blade by a connecting piece, such that (all) stresses exerted on the first and second bearing rings simultaneously pass through said connecting piece,

and/or, in a radial plane with respect to the blade axis, for at least one of the first and second bearing rings, the connection position of the bearing ring with respect to the connection element and the connection position between the bearing ring and the blade are located at different radial distances from the blade axis.

The above features, and as will be described in more detail below, not only improve the reliability of the wind turbine, but also improve the ergonomics of assembly/disassembly by providing a technically efficient and economical solution.

In view of optimizing the strength of the roller bearing in the radial direction, it is recommended that the bearing further comprises a retaining element or retaining portion mechanically connected to the connecting element or rotor hub and retained at least in the radial direction with respect to the axis of the blade by interfacing with the outer surface of the bearing ring radially furthest from the axis of the blade in the radial direction of said axis, so that upon rotation of the blade, stresses are resisted which separate at least some of the bearing rings from each other and/or which deflect the bearing ring radially furthest from the axis of the blade.

According to an alternative, it is conceivable: the first bearing ring, which is radially furthest from the blade axis, has a radial thickness at the end closest to the blade which is greater than the radial thickness at the end closest to the rotor head, and the outer surface of the bearing ring has a generator which is not parallel or not continuously parallel to the blade axis.

Drawings

Figure 1 is a front view of a wind turbine according to the invention,

figure 2 is a side view of the device,

FIG. 3 is a plan sectional view along line III-III, which is consistent with the rotor head and blades discussed herein,

FIGS. 4, 5 and 6 are views of the same section of three different embodiments,

figure 7 is a view of the three bearing rings alone in the previous figures,

figure 8 is an alternative to figure 4 using another roller bearing,

fig. 9 is an alternative to fig. 3, which uses a larger blade diameter, with the connection of the bearing ring being located outside the blade by means of a connection element.

Detailed Description

Fig. 1 and 2 show a wind turbine 1 comprising a post 3 on which three blades 5a, 5b, 5c are mounted, the blades rotating about a horizontal axis 7a of a central hub 7.

Usually, the hub 7 itself is mounted so that it can rotate about a vertical axis 7b with respect to the tower 3, which can be optimally oriented with respect to the wind.

Each blade, in particular blade 5c in fig. 2, can rotate around its extension axis 50c through a few to a few tens of degrees in relation to the rotor head 7, which best captures the wind.

Fig. 3 shows the axis 50c of the blade 5c, and the rotor head 7.

The preferred angular pitch of each blade, such as blade 5c, can produce substantial radial stresses as well as large bending moments.

The bearing 9 shown in fig. 3 is a double row roller bearing 11a, 11 b.

The bearing comprises an outer bearing ring 13, an inner bearing ring 15 and an intermediate bearing ring 19. The three bearing rings are concentric with the axis 50c and all extend in a generally radial plane 21 relative to the axis 50 c.

The intermediate bearing ring 19 is connected to the rotor head 7, while the outer bearing ring 13 and the inner bearing ring 15 are connected to the rotor blade 5c by means of separate connections or separate connection elements 23.

The connection element 23 is arranged in a direction substantially parallel to the axis 50c, in which case for the blade 5c the inner bearing ring 15 is connected directly to the blade via the connection 25, whereas the connection of the outer bearing ring 13 to the blade is indirect, since it is connected to the connection element 23 via the connection 27.

In fig. 3, the radial distance d1 is greater than d2 in plane 21.

The first bearing ring 13 is positioned radially beyond the blades. Its axial connections 27, here bolts, project outwards at the opposite axial ends of the bearing ring, which in this case is easily accessible, which are fixed by means of screw heads 27a or nuts 27 b.

The connector 25 is located at an inner diameter d2 and also includes a threaded rod accessible from its clamping end 250b, in this case a nut 25b, which is located on the opposite side of the hollow interior 31 of the rotor head 7.

It should be noted that: the hollow interior 31 and the hollow interior 500c of the blade are in axial communication via an inner bearing ring 15 and a continuous intermediate interior of a connecting element 23, which connecting element 23 is inserted parallel to the axis 50c between the bearing rings 13, 15 and between the blades with which they are in contact.

At its other axial end 250a, the threaded rod 25 is screwed into the body of the blade 5 c.

The unthreaded section between the two ends of the rod 25 passes through the second bearing ring 15 and the connecting element 23.

The connection in this example is therefore preferably axial, which ensures that at least one of the two bearing rings 13, 15 connected to the connecting element 23 at different radial distances from the blade axis is stressed.

In this case, the first bearing ring 13 is connected directly to the connecting elements 23 and not to the blade, whereas the second bearing ring 15 is connected to the blade via the connecting elements 23 and/or through the connecting elements 23, so that a connection to the blade is produced through which stresses exerted on the first and second bearing rings are transmitted.

Located at the intermediate diameter d3 is the intermediate bearing ring 19 and its connecting piece 29, which at one end (the nut 29b) projects into the hollow interior 31 and at the other end (the bolt head 29a) into the interior 33, is radially delimited by the cylindrical inner and outer walls of the two bearing rings 15, 13, axially by a flat wall of the bearing ring 19 in contact with the bolt head 29a and at the other end by a concave surface 230 on the connecting element 23.

The clamping end of the bolt 29, which opens into the interior 33, is prevented from rotating by a retaining projection 35 which is connected to the bearing ring 19 or the connecting element 23.

The bearing ring 19 is thus fixed to the rotor head 7, in this case clamped parallel to the axis 50c from the hollow interior 31.

In this way the connection of the three bearing rings 13, 15, 19 is easily accessible, each end bearing ring 13, 15 being fixed to the intermediate radial connection element 23, instead of being fixed directly to the blade.

As shown in fig. 3, the connection element 23 is connected to the blade with a connection at a single radius without a special connection of the bearing rings 13, 15 to the blade 5 c.

In fig. 3, it can also be noted that: the outer peripheral surface 13a of the outer bearing ring 13 is at least radially fixed relative to said blade axis 50c by means of a retaining element 231 mechanically fixed to the connection element 23, such that radial stresses that separate at least some of said first, second and third bearing rings from each other and/or stresses that deflect the bearing ring 13, 130 radially furthest from the axis of the second element are resisted when the blade is rotating or, more generally, when the wind turbine is operating.

In this case, the retaining element 231 is connected tightly to the connecting element 23 by way of an integral formation and extends as a shoulder which is in radial contact with the outer circumferential surface 13a of the bearing ring 13 in the region 130.

Alternatively, it is also conceivable to provide the connection by other connection means, such as screwing, welding, etc., so that a specially shaped element is formed when the one-piece forming section 231 is fixedly and rigidly connected to the connecting element 23.

In the case of a total failure-weakening solution, one possible alternative is to envisage the rotor head 7 having a radial projection 71 with a shoulder 700 which is in radial contact with said outer surface 13a, but which is in axial contact with said outer surface 13a on the side of the opposite end of the bearing ring 13, i.e. towards the end closest to the rotor head 7.

The shoulder 700 may even be part of a connection element 800 (dotted line in fig. 3) between the rotor head 7 and the bearing ring 19, through which the part 29 passes for connection to the rotor head.

Between the intermediate bearing ring 19 and said first and second bearing rings 13, 15 there are at least two sets of roller bearings, respectively.

The roller bearing in this example is a spherical roller bearing.

In the solution illustrated in fig. 3, there are two rows of roller bearings 37a, 37b and 39a, 39b arranged in groups of two, each of which is axially offset in the direction 21 parallel to the axis 50c at a different radial distance.

Fig. 4 shows the same components and the same arrangement as in fig. 3, but the connection between the connecting element 23 (in this case the reference 23a) and the blade 5c is different, here three ball bearings are used which are fully adapted as the two sets of two-row four-roller bearings in fig. 3.

The connecting element 23a has, on the opposite side to the aforesaid internal cavity 150, a monolithic portion 233 provided with an axial hole 41 (parallel to the axis 50c), the radial distance between said axial hole 41 and the axis 50c being d4, d4 being smaller than the distances d1, d2, d3 previously described in figure 3. Each of which has inserted therein only one of the fourth connections 43, the connection element 23a (also annular like the element 23) being directly connected to the blade 5c, while the first outer bearing ring 13 and the second bearing ring 15 are connected to the connection element 23a only at different radial distances, in this case d1 and d5, respectively.

The connecting elements in the example described correspond to, for example, the bolts 27 and 45, respectively, one being screwed in by means of a screw head and the other being mounted inside or outside the rotor head 7 by means of a threaded end of a screw provided with nuts 27b and 45b, the screw corresponding to the bolt 45 being inserted into the hollow interior 31.

As the screw is screwed into the blade at the end opposite the cavity 150 and tightened at the opposite side with a plurality of nuts 43b, the stress thus passing through the two outer bearing rings 13, 15 is transmitted to the connecting element 23a and, via the connecting piece 43, to the blade 5 c.

For the roller bearings, the third roller bearing 47 is also a ball roller bearing, but larger than the other two roller bearings 37a, 37 b.

The third roller bearing 47 and the roller bearings 37a, 37b are each offset in the radial and axial directions (directions parallel to the axis 50 c). The projection line of the third roller bearing 47 in the direction orthogonal to the axis 50c is located between the projection lines of the two roller bearings 37a, 37 b.

At a radial distance d4 from the axis 50c, the connecting element 23a is connected to the blade there, and at different distances d1 and d5, the first and second bearing rings 13, 15 are independently connected to the connecting element 23 a.

In fig. 4, the connection of the intermediate bearing ring 19 is the same as that shown in fig. 3.

In the solution of fig. 4, it is of course also possible to choose to use two sets of double row roller bearings 37a, 37b and 39a, 39b as shown in fig. 3.

Alternatively, when the diameter of the blade, in particular of the blade 5c, is larger than in the blade shown in fig. 3, the connection to the blade via the connecting element 23 can also be realized by replacing the inner bearing ring 15 with the outer bearing ring 13, as shown in fig. 9.

For the connection parallel to the axis 50c, the connecting pieces 25 and 27 can be interchanged in such a way that the inner bearing ring 15 is connected by means of the bolts 27, the bolts 27 extending on one side into the hollow interior 31 and on the other side into the cavity 500c (which is radially wider), the connecting piece 25 protruding from the outside (at the area 46 in fig. 3) passing axially through the outer bearing ring 13 and being screwed into the blade body by means of the threaded portion 250 a.

It should be noted that the threaded section 250a in fig. 3 is screwed only into the blade body 5c, whereas the threaded section 250b is only engaged with the nut 25 b.

In this preferred embodiment, neither the separate element 23 nor the bearing rings 13, 15 are threaded.

Fig. 5 shows a rotor head 70 and a wind turbine blade 5c with a slightly larger diameter than the blade of fig. 3 and 4.

The bearing still comprises a first outer bearing ring 130 (radially of the axis 50c), an inner bearing ring 150 and an intermediate bearing ring 190.

The bearing rings are mounted at different diameters relative to the axis 50c, see d12, d13 and d14 in fig. 5, and the same reference numerals are used in fig. 6.

Fig. 7 shows these connections: each bearing ring has a connection to the blade or rotor hub at each pitch P of the same diameter, e.g. diameter d2 in fig. 3, and the connection of the inner bearing ring 15 at the same pitch P is connected to the blade, and similarly there are connections between the bearing ring 15, the connection element 23 and the blade to each other. Figure 7 does not show roller bearings.

With reference to the above description of the solution, fig. 5 and 6 show the connection of the intermediate bearing ring 190 at the root of the blade 5c, respectively, when the two outer bearing rings 130, 150 are directly connected to the rotor head 70, in this case all parallel to the extension axis 50c of the blade 5 c.

More specifically, the bearing ring connections 27, 49 are both directly connected to a connection 51 with a local concave surface 510, which connection 51 is tightly mounted on the rotor head 70, which connection 51 extends in said direction 21 in a radial direction of the blade axis in relation to the blade axis up to the opposite side of the outer bearing rings 130 and 150, and the oppositely located connection 53 connects the intermediate bearing ring 190 to the root of the blade 5 c.

In this case, the connecting element 53 can, like the connecting element 25 in fig. 3, in this case comprise a threaded rod with a clamping head 55 which is located in a closed chamber extending to the opposite side of the surface 510, like the chamber 33 shown in fig. 3.

Fig. 6 shows the same arrangement except that the two sets of roller bearings 37a, 37b and 39a, 39b of fig. 5 are replaced by the previously mentioned double row of bearings 39a, 39b at the smaller diameter d7 and a set of large diameter spherical roller bearings 47 at the larger diameter d 8.

Alternatively, the bearing set of roller bearings 47 may be located at diameter d7, while the two sets of spherical double roller bearings of smaller diameter may be located at diameter d8, as shown in FIG. 4.

In fig. 5 and 6, therefore, it is no longer necessary to provide a shoulder on the connecting element for radially retaining the outer bearing ring 13, as in fig. 3 and 4.

As an alternative, the outer bearing ring 130 is furthest from the axis 50c, with an increasing radial thickness e.g. e1 towards the blade end 130a and a decreasing thickness towards the rotor head 70 end 130b (see thickness e2 in fig. 6, where e2 is smaller than e 1).

Thus, the bearing ring 130 has an outer peripheral surface 130c that abuts a generator 130d that is not parallel to the axis 50c or is not continuously parallel to the axis 50 c.

The outer peripheral surface 130c in this example is a slope with respect to the axis 50 c. It may also be a step or shoulder of increasing thickness from e2 to e1 near end 130 a.

The increased radial thickness is preferably at least 20%.

Note that the outer bearing rings 130, 150 shown in fig. 5 and 6 directly connected to the rotor head connection portion 51 have different radial distances from the third bearing ring 190 connected to the root of the blade 5 c.

In these figures, the connecting section or portion 51 and the extended rotor head 70 form a single piece, T-shaped in cross-section, with the stem portion extending axially as the main body of the rotor head, and the other parts housed in the cross-beam portion, with one side 51a housing the clamp connection of the connector 27 and the other side 51b housing the clamp connection of the connector 49, said connector 49 having one end inserted into the hollow interior 310 of the rotor head 70 and the axially opposite end inserted into the interior 500d of the blade 5c, the interior 500d having an internal diameter d9 slightly larger than the internal diameter d10 of the blade in fig. 3 and much larger than the internal diameter d11 of the blade in fig. 4.

In fig. 5 and 6, the inner cavity 500d communicates with the hollow inner cavity 310 via the inner cavities of the intermediate bearing ring 190 and the inner bearing ring 150 and the end forming the connecting portion 51.

It is also possible to use only two bearing rings. The inner bearing ring 15 or 150 and thus the roller bearings between the bearings and the bearing ring 19 or 190 may be eliminated.

Although the above-described solution does not appear to be suitable for large wind turbines, a person skilled in the art will also envision other uses of the solution presented in the present application, in particular for large cranes.

It should be noted that, in the radial direction of the blade axis, instead of the arrangement order of the fourth connecting piece 43, the third connecting piece 45 and the first connecting piece 27 from the axis in fig. 4, the following arrangement order may be used: a third connector 45, a first connector 27 and a fourth connector 43. The blades, being not radially inwardly directed, will have a larger diameter than the rotor head 7. In fig. 3 it is also possible to connect only the inner bearing ring 15 to the connection element 23, by means of which the outer bearing ring 13 is connected to the large diameter blade, so that the stresses of the bearing ring 15 and of the connection between it and the blade can be transmitted to the outer bearing ring.

The solution of fig. 8 is to use at least four ball roller bearings 37a, 37b, 39a, 39b instead of the three roller bearings of fig. 4.

Claims (11)

1. Device for a wind turbine or a large crane comprising a pivot bearing of a servo actuation device between a first element (7) and a second element (5c), the second element and the bearing having the same axis, the device comprising:

-axial first and second bearing rings (13, 15; 130, 150) of different diameters in a radial direction with respect to an axis (50c) of the second element (5c),

-a connecting element (23, 23a) interposed between the second element and the first and second bearing rings (13, 15; 130, 150), the connecting element (23, 23a) being parallel to said axis,

-an axial third bearing ring (19) positioned radially between the first and second bearing rings with respect to the axis of the second element, the third bearing ring being connected to the first element (7), the connecting element and at least one of the first and second bearing rings being connected to the second element,

characterized in that said connecting element (23, 23a) extends in a radial direction with respect to the axis of said second element (5c) with respect to said first and second bearing rings (13, 15; 130, 150) to which it is connected, and

at least one of the first and second bearing rings (13, 15; 130, 150) is connected to the connecting element (23, 23a) and not to the second element (5c), but the connecting element (23, 23a) is connected to the second element (5c) by means of a connecting piece (25, 43) engaged between the connecting element (23, 23a) and the second element (5 c).

2. A device according to claim 1, wherein each of the first and second bearing rings (13, 15) is directly connected to a connecting element (23a) and not directly to the second element (5c), said connecting element being connected to said second element, in a radial plane with respect to said axis of said second element, by means of said connecting piece (43) which is not dedicated to any one of these bearing rings, so that the stresses exerted simultaneously on the first and second bearing rings (13, 15) pass through said connecting piece (43).

3. The apparatus of claim 1, wherein:

-the first bearing ring (13; 130) radially furthest from the axis of the second element is directly connected to the connecting element (23) instead of to said second element, and

-said second bearing ring (15; 150) being connected to said connecting element and to said second element (5c) by said connecting piece (25) in a radial plane with respect to the axis of said second element, so that the stresses exerted simultaneously on the first and second bearing rings pass through said connecting piece (25).

4. The arrangement according to claim 1, characterized in that for at least one of the first and second bearing rings (13, 15; 130, 150) the connection position of the at least one of the first and second bearing rings (13, 15; 130, 150) to a connection element (23, 23a) and the connection position between the bearing ring and a second element (5c) have different radial distances (d1, d 2; d4, d5) relative to the axis of the second element in radial planes relative to the axis of the second element.

5. The device according to claim 1, characterized in that the connection piece (25, 41) for connection to the second element passes through the connection element (23, 23a) at a first radial distance (d2, d4) from the axis of the second element, the first bearing ring (13) being connected to the connection element at a second radial distance (d1) from the axis of the second element, the second radial distance (d1) being different from the first radial distance.

6. A device according to claim 1, characterized in that the device further comprises a retaining element (231) mechanically connected to the connecting element (23, 23a), the retaining element interfacing with the outer surface (13a) of the one bearing ring radially furthest from the axis of the second element so that upon rotation of the second element radial stresses are resisted which separate at least some of the first, second and third bearing rings from each other and/or which deflect the one bearing ring (13, 130) radially furthest from the axis of the second element.

7. The apparatus of claim 1, wherein:

-the bearings comprise two sets of roller bearings (37a, 37 b; 39a, 39 b; 47), one set of roller bearings extending between the first and third bearing rings and the other set of roller bearings extending between the third and second bearing rings.

8. The apparatus of claim 7, wherein: one of the sets of roller bearings comprises a single roller bearing (47), the single roller bearing (47) being larger than the roller bearings (37a, 37b, 39a, 39b) in the other of the two roller bearings, a line of projection of the single roller bearing (47) in a direction orthogonal to the axis (50c) being located between lines of projection of the other of the two roller bearings in the direction orthogonal to the axis.

9. The device according to claim 1, wherein the connecting element (23, 23a) has a concave surface (230), the third bearing ring (19) being attached to the first element (7) by means of a further connecting piece (29), said further connecting piece (29) having a bolt head (29a) which is separately received in a cavity which is radially delimited by the cylindrical inner and outer walls of the first and second bearing ring, which cavity is axially delimited at one end by the flat wall of the third bearing ring (19) which is in contact with the bolt head (29a) and at the other end by said concave surface (230).

10. The apparatus of claim 1, wherein:

-the first element is a rotor hub of a wind turbine,

-the second element is a blade of a wind turbine.

11. The apparatus of claim 1, wherein: between the first bearing ring and the third bearing ring (13, 130; 19), on the one hand, and between the second bearing ring and the third bearing ring (15, 150; 19), on the other hand, respective rolling bearings (37a, 37b, 47, 39a, 39b) are arranged.