This application claims the benefit of European Patent Application EP17382273 filed on May 15th, 2017.

The present disclosure relates to counterweights, particularly reel counterweights for traction wires. The present disclosure further relates to wire-tractioned lifts and wind turbines comprising such reel counterweights. BACKGROUND

Wire-tractioned lifts are commonly used for the transportation of people and/or equipment which are hoisted up and down within vertical structures such as wind turbine towers or mine shafts, for instance. Wires or ropes are extended from a top to a bottom of the tower or shaft.

Wire-tractioned lifts which may be alternatively known as wire-tractioned service lifts, may be suspended by a traction wire rope. Service lifts can be hoisted up and down along the traction wire rope by means of a traction hoist.

The traction wire rope is usually hanging from a top suspension beam placed at the top of the tower or shaft and the traction wire rope is tensioned by its own weight plus an additional counterweight of a predefined weight (for instance, 1 1 kg), which is typically attached at the bottom end of the wire traction.

The counterweight is installed typically at the tower or shaft basement, below the bottom limit of the service lift path. As the elevator moves up and down the elevator path, the counterweight moves as well. The counterweight ideally must be able to turn about its own rotational axis and move up and down along a predefined distance (for instance, approximately 30 cm) without encountering or damaging any obstacle. Otherwise, the obstruction of the free movement of the counterweight will cause the early damage of the traction wire rope. The counterweight is typically fixed to the traction wire rope.

A portion of the ends of the traction wire rope may be processed to keep tips of strands joined and compact. That processed portion allows the traction wire rope entering the motor whenever it is necessary, for instance, during maintenance works. Processing of the end portion may be done during manufacture and before the traction wire is delivered to the client. The overall length of the wire rope may not be perfectly adapted to the size of a specific tower or shaft and the excess portion cannot simply be cut. As a consequence, an excess of wire rope is obtained which is usually coiled below the counterweight and fixed, for instance by means of plastic cable ties.

In different implementations and in particular in wind turbines, such an arrangement may involve several drawbacks:

-There are situations in which there is not enough clearance in the basement to allow the counterweight to move up and down along a predefined distance, plus the height of the counterweight and the wire coil below the counterweight. By way of example, basements of wind turbine towers are currently configured to save as much space as possible, which may reduce the clearance available in the basement.

- The size and shape of the wire rope coil below the counterweight are very much dependent on the skills and experience of a technician installing the wire rope. Features of the coil may vary from one case to another so no uniform coils are obtained. The formation of the coil is also prone to installation mistakes by technicians. In order to save space and reduce the risk of installation mistakes, a highly-qualified/trained technician is required.

- The excess of wire rope which is coiled may be supported on the floor of the basement. The traction wire rope cannot rotate easily around its own longitudinal axis, so the wire rope may then become frayed as it moves in reaction to movements from the elvator. The floor of the basement may also be dirty or wet which may contribute to wear of the wire rope.

If there is no clearance enough in the basement, the user may attempt to wound the excess of wire rope around the counterweight in an uncontrolled manner. This results in a bulky and messy build-up of wire rope which provides the counterweight with an outsized volume. This outsized volume can cause the counterweight to get stuck because of the obstacles encountered during displacement of the counterweight. Similar problems may occur with counterweights in other constructions.

It is an object of the present disclosure to provide examples of reel counterweights and methods for counterweighting that avoid or at least reduce one or more of the afore-mentioned drawbacks.

SUMMARY In a first aspect, a reel counterweight for tensioning a traction wire is provided. The reel counterweight comprises a winding drum to receive at least an end portion of the traction wire coiled around a peripheral surface of the drum. The reel counterweight also comprises one or more guiding elements to confine the coiled traction wire around the drum. The winding drum comprises an inside cavity, comprising a first opening for receiving the traction wire in the inside cavity, and a second opening for guiding the traction wire from the inside cavity to the peripheral surface of the drum.

According to this aspect, a space-saving reel counterweight is obtained since the coil formed by the excess of the traction wire is wound around the winding drum.

Thanks to the space-saving configuration, the requirements of clearance in the basements can be significantly reduced. Consequently, a basement may be envisaged with a relatively reduced clearance which is enough for allowing the reel counterweight moving up and down along a predefined distance, plus the height of the reel counterweight. The height of the wire coil below the counterweight is no longer considered. The size and shape of the wire rope coil are no longer dependent on the skills of a technician since the wire rope is wound around the peripheral surface of the winding drum and confined by the guiding elements. Therefore, features of the coil are uniform from one case to another and predictable. Furthermore, it is also reduced the possibility of installation mistakes from technicians. The reel counterweight may freely rotate around its own longitudinal axis avoiding contact with the floor of the basement. Therefore, the wear of the end portion of the traction wire rope may be reduced and the risk of becoming frayed may be avoided.

The traction wire rope may be wound around the peripheral surface of the winding drum in an orderly and tidy manner, avoiding any bulky and messy build-up of wire rope around the counterweight which may cause the reel counterweight to get stuck.

According to that aspect a reel which may be used for winding the traction wire and at the same time may be used as a counterweight for tensioning the traction wire, is obtained. Throughout the present disclosure, expressions such as above, below, beneath, under, upper, bottom, etc are to be understood taking into account the construction of an elevator or the like in an operating condition as a reference. Throughout the present disclosure, the terms "lift" and "elevator" are used interchangeably. The terms "elevator cabin" or "elevator car" are used to indicate a structure that is used for housing people and/or goods as they are moved up and downwards by the elevator. Throughout the present disclosure, the terms "longitudinal axis" and "central axis" are used interchangeably.

Throughout the present disclosure, a path is to be understood as a space or passage through which the lift or the like can travel upwards and downwards. In a wind turbine tower, the elevator path is thus defined inside the tower.

There may be a closed space inside the tower along which an elevator cabin travels. Alternatively, the space inside the tower through which the elevator travels may be open. In a further aspect, the present disclosure provides a wire-tractioned lift which may comprise a reel counterweight as hereinbefore described. In another aspect, the present disclosure provides a wind turbine tower which may comprise a reel counterweight as hereinbefore described.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:

Figure 1 schematically shows a view in perspective of a reel counterweight according to an example;

Figure 2 schematically shows a side view of the reel counterweight of figure 1 ;

Figure 3 schematically shows a cross sectional view of the reel counterweight of figure 2 taken along line A-A';

Figure 4 schematically shows a view in perspective of a reel counterweight according to a further example; Figure 5 schematically shows a side view of the reel counterweight of figure 4;

Figure 6 schematically shows a cross sectional view of the reel counterweight of figure 5 taken along line B-B'; Figure 7 schematically shows a view in perspective of a reel counterweight according to a further example;

Figure 8 schematically shows a side view of the reel counterweight of figure 7; Figure 9 schematically shows a cross sectional view of the reel counterweight of figure 8 taken along line C-C;

DETAILED DESCRIPTION OF EXAMPLES In attached figures the same reference signs have been used to designate matching elements. Figure 1 schematically shows a view in perspective of a reel counterweight 1 according to an example. Figures 2-3 also relates to the example of reel counterweight 1 of figure 1 , wherein figure 2 schematically shows a side view thereof, and figure 3 schematically shows a cross sectional view thereof taken along section line A-A'. The reel counterweight 1 for tensioning a traction wire 100 may comprise:

A winding drum 2 to receive at least an end portion of the traction wire 100 coiled around a peripheral surface 21 of the drum 2. The reel counterweight 1 in this example may further comprise two guiding elements to confine the coiled traction wire 100 around the drum 2. The number of guiding elements may vary from one example to another and it may be one or more. In the examples of figures 1 -3 the guiding elements comprise a pair of end plates 41 provided respectively at opposing ends of the winding drum 2 and projecting radially outwardly from the peripheral surface 21 of the drum 2. Since the plates extend radially beyond the peripheral surface, the wire rope can be kept between the end plates, and cannot slip off from the reel.

As can be seen in figure 3, the winding drum 2 may comprise an inside cavity 22. The inside cavity 22 may comprise a first opening 31 or incoming opening for receiving the traction wire 100 in the inside cavity 22, and a second opening 32 or outgoing opening for guiding the traction wire 100 from the inside cavity 22 to the peripheral surface 21 of the drum 2. According to some examples, the cross section of the drum 2 may be circular or have a generally rounded shape which avoids the reel counterweight 1 getting stuck in case of collision with any obstacle. By way of example, the winding drum 2 may comprise a generally tubular body. The end plates 41 may be configured as discs.

In some other examples, the end plates 41 may comprise beveled edges 43, which helps the reel counterweight 1 to not be stuck in case of collision with any obstacle while turning around its rotational axis (not illustrated) and while the reel counterweight 1 moves up and down.

The portion of the traction wire 100 on the winding drum 2 may extend between an end tip 101 of the loose traction wire 100 portion and the lowest part of the tensioned traction wire 100 portion which may be just before entering the first opening 31 . The first opening 31 may connect the inside cavity 22 with the bottom portion of the tensioned traction wire 100 and the second opening 32 may connect the inside cavity 22 with the loose portion of the traction wire. All in all, there may be a difference of tension: the tension in the tensioned traction wire 100 portion may be higher than the tension of the loose traction wire 100 portion. Loose portion or loose traction wire 100 portion may be understood as a segment of the traction wire 100 not tensioned by the reel counterweight 1 and not wound around thereof.

On the one hand, the first opening 31 may be arranged along a central axis CA of the winding drum 2. On the other hand, the second opening 32 may be provided in the peripheral surface 21 of the drum 2. Those arrangements should be understood as possible examples of position; other possible arrangements may be envisaged as it will be described later. The central axis CA may coincide with a rotational axis (not illustrated) of the reel counterweight 1 . Figures 1 -3 show an example where central axis CA coincides with the rotational axis. In other examples, the central axis CA may be substantially perpendicular to the rotational axis of the reel counterweight 1 , i.e. the central axis CA may differ from the rotational axis.

The reel counterweight 1 may further comprise a first wire lock 51 to clamp on the traction wire 100, such that the traction wire 100 may be fixed relative to reel counterweight 1 at the first opening 31 . In some examples, this first wire lock 51 may be positioned in the inside cavity

22 which is just below the first opening 31 , taking into account the direction of the traction wire 100 entering the inside cavity 22.

According to one example, the first opening 31 may be provided in the end plate 41 . This first opening 31 may be provided in other locations as it will be described later. In further examples, the reel counterweight 1 may comprise a fastening member for fastening a loose portion of the traction wire 100 to the reel counterweight 1 . As depicted in figures 1 -3, the fastening member may comprise a third opening 33 provided, for instance, in the end plate 41 for passing through an end portion of the traction wire 100.

When a third opening 33 is provided, the reel counterweight 1 may also comprise a second wire lock 52 to clamp on the loose end portion of the traction wire 100, such that the end portion may be fixed relative to reel counterweight 1 at the third opening 33.

In a further non-illustrated example, the reel counterweight 1 may comprise two fastening members arranged such that the end portion describes a loop (not illustrated) therebetween.

According to an example, at least one of the openings 31 , 32, 33 may comprise a sleeve 34. This sleeve 34 may protect the traction wire 100 from the pressure exerted by a corresponding wire lock.

Figure 4 schematically shows a view in perspective of the reel counterweight 1 according to a further example. Figure 5 schematically shows a side view thereof, and figure 6 schematically shows a cross sectional view thereof taken along section line B-B'.

Figures 4 - 6 show an example of the reel counterweight 1 wherein the first opening 31 is provided in the peripheral surface 21 of the winding drum 2. Unlike the example of figures 1 -3, now the first opening 31 is not arranged along the central axis CA of the winding drum 2 but substantially perpendicular thereto. A first wire lock 51 is provided as described above. In this example, the second opening 32 is arranged in the peripheral surface 21 of the drum 2. In the examples of figures 4 - 6 the central axis CA along which the first opening is arranged (which substantially coincides with the longitudinal axis of the traction wire rope) is substantially perpendicular to the rotational axis of the reel counterweight 1 .

As above described, the fastening member may comprise a third opening 33 provided in the end plates 41 with corresponding second wire lock 52. However, other locations may be envisaged.

Figure 7 schematically shows a view in perspective of a reel counterweight 1 according to a further example. Figure 8 schematically shows a side view thereof and figure 9 schematically shows a cross sectional view thereof taken along section line C-C

In figures 7 - 9 an example is illustrated wherein the guiding elements comprise rods 42 provided respectively at opposing ends of the winding drum 2. These rods 42 project radially outwardly from the peripheral surface 21 of the winding drum 2 so as to confine the coil of the traction wire 100. By way of example, at each opposing end of the winding drum 2 a pair of rods 42 may be positioned diametrically opposed to each other. In some examples not illustrated, the number of rods 42 may vary. Winding drum 2 may have two "open" opposite ends as per figures 7-9. In that case, if the second opening 32 is provided in the peripheral surface 21 of the winding drum 2, the second opening 32 may open out to the "open" opposite ends of the drum 2. The example of figures 7 - 9 also show a reel counterweight 1 wherein the first opening 31 is provided in the peripheral surface 21 of the winding drum 2. That is to say, the first opening 31 is not arranged along the central axis CA of the winding drum 2 but substantially perpendicular thereto. In the examples of figures 7 - 9 the central axis CA is substantially perpendicular to the rotational axis of the reel counterweight 1 .

As illustrated in figure 8, the fastening member may comprise a third opening 33 which may be positioned in the peripheral surface 21 of the winding drum 2. Figure 8 illustrates an example of reel counterweight 1 where the third opening 33 is positioned this way. In some examples the reel counterweight 1 may be a steel weldment with the shape of a reel where the excess of traction wire 100 may be coiled around the peripheral surface 21 . Instead of steel, any other suitable material may be chosen and end plates 41 and winding drum 2 may be joined to each other by any suitable method, not only by welding. Alternatively, end plates 41 and winding drum 2 may be integrally formed.

According to some examples, the first opening 31 and/or the second opening 32 and/or the third opening 33 may be configured as bores.

In some examples, the first opening 31 may be provided in the end plates 41 or peripheral surface 21 .

In some examples, the second opening 32 may be provided in the peripheral surface 21 , end plates 41 or an open end of a generally tubular winding drum 2.

In some examples, the fastening member may be provided at the end plate 41 or at the peripheral surface 21 .

Alternatively to the third opening 33, the fastening member may comprise a welding, a retainer, a bracket, a recess or similar.

In some examples, the first opening 31 and the second opening 32 may be aligned with each other.

In one example, the second opening 32 may be a rectangular hole in the peripheral surface of the winding drum 2, which facilitates the traction wire 100 to be passed through the second opening 32 and consequently to be wound around the peripheral surface 21 .

In examples as those illustrated in figures 1 -6, the end plates 41 may be discs and the winding drum 2 may be a tube; discs may be welded at each end of the tube respectively.

In some examples not illustrated, the guiding elements may comprise a grooving on the drum 2, and the grooving may be disposed on the peripheral surface 21 to receive the coiled traction wire 100. The grooving may designed to receive a traction wire 100 with specific size and shape and confining the coil formed. The herein disclosed examples of the reel counterweight 1 may form part of a wire-tractioned lift. Such a wire-tractioned lift may be implemented in a wind turbine tower or in another structure.

In the following, an example of an operation of installing the reel counterweight 1 will be explained. This example regards a basement of a tower of a wind power generator.

The traction wire 100 hangs from a top suspension beam (not illustrated) placed at the top of the tower (not illustrated). At the bottom end of the traction wire 100 the reel counterweight 1 is intended to be attached to keep the traction wire 100 tensioned.

The weight and size of the reel counterweight 1 are specifically chosen for each case. For example, the reel counterweight 1 may be approximately 15 cm high, and may be suitable to be installed in basements with clearance from approximately 45 cm high.

In order to attach the reel counterweight 1 to the traction wire 100, the operator may enter an end portion of the traction wire 100 into the inside cavity 22 through the first opening 31 . Then the operator may pass the traction wire 100 through the second opening 32 from the inside cavity 22. The reel counterweight 1 may at this stage be slanted, such that the central axis CA of reel counterweight 1 may be tilted with respect to the length of the traction wire 100 to make the installation of the reel counterweight 1 easier, for instance in that example illustrated in figures 1 -3 where the second opening is arranged in the peripheral surface 21 . This way, the first opening 31 and the second opening 32 may be aligned with each other along the traction wire 100. However, this alignment could alternatively be achieved thanks to the location of the first opening 31 relatively to the second opening 32 in the reel counterweight 1 .

The end portion of the traction wire 100 may comprise a processed tip 101 so as to maintain the strands of the wire rope joined. This may be useful when the traction wire 100 is entered through the first opening 31 and the second opening 32. The operator may place the reel counterweight 1 at a predefined distance from the bottom limit of the service lift path (and beneath it). This distance may be 300 mm, for instance.

Afterwards, the operator may place the first wire lock 51 on a corresponding sleeve 34. Then the reel counterweight 1 may relatively move along the traction wire 100 in such a way that the first wire lock 51 may enter the inside cavity 22 through the second opening 32. The second opening 32 may be particularly configured to admit the first wire lock 51 , for instance may be a rectangular hole in the peripheral surface of the winding drum 2. This hole may show suitable dimensions in order to admit that first wire lock 51 .

Once the first wire lock 51 is placed in the inside cavity 22, the relative movement of the reel counterweight 1 along the traction wire 100 is stopped when the first wire lock 51 abuts the reel counterweight 1 and consequently the sleeve 34 may be housed inside the clearance of the first opening 31 , where the ends of the sleeve 34 may protrude at both sides of the first opening 31 . Therefore the first wire lock 51 may be positioned on the sleeve 34 in a side where the first opening 31 opens out to the inside cavity 22. This way, the first wire lock 51 may support the reel counterweight 1 .

As above mentioned, the first opening 31 may be positioned in several locations of reel counterweight 1 . In any case, the operator may provide the first wire lock 51 in order to fix the traction wire 100 relative to reel counterweight 1 .

The second opening 32 may be a hole specifically shaped to allow the traction wire 100 to leave the inside cavity 22 without constraint so as to be wound around the peripheral surface 21 . By way of example, the second opening 32 may be rectangular-shaped. The operator may take advantage of the guiding elements for forming the coil of the traction wire 100 as it confines the coil. According to the present example, the guiding elements comprise two end plates 41 , although it may comprise rods 42 or a grooving.

Depending on the length of the portion of the traction wire 100 to be wound, the operator may dispose the traction wire 100 in several rounds or layers, e.g. three rounds. The outermost round or layer may be protected owing to the end plates 41 or the rods 42, projecting from winding drum 2.

Once the coil of traction wire 100 has been formed around the peripheral surface 21 , the operator may attach the traction wire to an edge of the counterweight reel using a fastening member. In this specific example, the traction wire 100 is passed through a third opening or recess 33. This third opening 33 may be positioned in several locations of the reel counterweight 1 and may comprise a sleeve 34 inside the clearance of the third opening 33, and the ends of the sleeve 34 may also protrude at both sides of the third opening 33. The sleeve 34 may be installed inside the third opening 33, by passing the loose end portion of the traction wire 100 through the sleeve 34 and moving the sleeve 34 along the traction wire 100 until the sleeve 34 may be housed inside the clearance of the third opening 33. Such a sleeve 34 can also be separate, and mounted on a portion of the traction wire, after which the sleeve may be passed through the third opening 33 (or other fastening member).

The second wire lock 52 may be positioned on the sleeve 34 of the third opening 33, so that the loose end portion of the traction wire 100 is kept fixed relative to the reel counterweight 1 and does not move back through the third opening 33. Therefore, the coil of traction wire 100 may not become unravelled. As above mentioned, the fastening member may comprise other configurations which avoid the coil of traction wire 100 becoming unravelled.

When the reel counterweight 1 comprises two fastening members the end portion of the traction wire 100 may describe a loop therebetween. Each of the fastening members may comprise a third opening 31 so the loop may be described between the two third openings 31 . A second wire lock 52 may be placed at the "last" third opening 33 where the traction wire 100 is passed through.

The rotational axis of the reel counterweight 1 may run through the first opening 31 , since the rotational movement direction may be defined around the length of the portion of the traction wire 100 entering the first opening 31 . Direction of rotational movement may be clockwise or counter-clockwise.

Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow. 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 guiding the scope of the claim.