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Title:
A WIND TURBINE
Document Type and Number:
WIPO Patent Application WO/2014/177531
Kind Code:
A1
Abstract:
The present invention relates to a wind turbine comprising a hub with one or more rotor blades connected to the hub, a nacelle, a bottom frame extending from the hub end of the nacelle towards the opposite end of the nacelle, the hub being connected with a main shaft arranged inside the nacelle, the main shaft having an outer diameter and extending from the hub towards an end of the nacelle opposite the hub, and rotating with a first rotational velocity, and a plurality of energy-generating devices each comprising a hollow shaft having an inner diameter and a planetary gearing system, the planetary gearing system being connected with the main shaft at a first end and with the hollow shaft at a second end. The plurality of energy-generating devices are arranged in succession of each other along the main shaft, the inner diameter of the hollow shafts being larger than the outer diameter of the main shaft, whereby the hollow shafts are arranged concentrically around the main shaft so that the energy- generating devices are all driven by the main shaft via the planetary gearing systems, and wherein the energy-generating devices are releasably connected to the bottom frame.

Inventors:
DRAGSTED HELLE RUDE (DK)
Application Number:
PCT/EP2014/058666
Publication Date:
November 06, 2014
Filing Date:
April 29, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
TINKERBELL APS (DK)
International Classes:
F03D9/00; F03D1/00; F03D11/02
Foreign References:
DE29706980U11997-07-10
DE102007059820A12009-06-18
US20080171630A12008-07-17
US20100253087A12010-10-07
US8358029B22013-01-22
Attorney, Agent or Firm:
HOFFMANN DRAGSTED A/S (København V, DK)
Download PDF:
Claims:
Claims

1. A wind turbine (1) comprising

- a hub (5) with one or more rotor blades (6) connected to the hub (5),

- a nacelle (4),

- a bottom frame (15) extending from the hub end of the nacelle towards the opposite end of the nacelle,

- the hub (5) being connected with a main shaft (7) arranged inside the nacelle (4), the main shaft (7) having an outer diameter (d0) and extending from the hub towards an end (8) of the nacelle opposite the hub, and rotating with a first rotational velocity, and

- a plurality of energy-generating devices (9) each comprising a hollow shaft (10) having an inner diameter (d,) and a planetary gearing system (11), the planetary gearing system being connected with the main shaft (7) at a first end (12) and with the hollow shaft at a second end (13),

wherein the plurality of energy-generating devices (9) are arranged in succession of each other along the main shaft (7),

the inner diameter (d,) of the hollow shafts (10) being larger than the outer diameter (d0) of the main shaft (7), whereby the hollow shafts (10) are arranged concentrically around the main shaft (7) so that the energy-generating devices (9) are all driven by the main shaft (7) via the planetary gearing systems (11), and,

wherein the energy-generating devices (9) are releasably connected to the bottom frame (15).

2. A wind turbine according to claim 1, wherein the bottom frame (15) has at least the same extension as the main shaft (7).

3. A wind turbine according to any of the preceding claims, wherein the energy-generating devices (9) are connected to the bottom frame (15) by means of bolts (70) or similar connecting means.

4. A wind turbine according to any of the preceding claims, wherein the energy-generating devices (9) are adapted to be slid on and along the bottom frame (15).

5. A wind turbine according to any of the preceding claims, wherein the bottom frame (15) comprises a set of rails arranged on each side of the main shaft (7) and is adapted to slidably support the energy-generating devices (9). 6. A wind turbine according to claim 5, wherein the energy-generating devices comprise wheels (75) or rollers adapted to slide or roll on the set of rails or the bottom frame (15).

7. A wind turbine according to any of the preceding claims, wherein the bottom frame (15) is arranged in relation to the main shaft (7) with the same distance along the extension of the main shaft (7).

8. A wind turbine according to any of the preceding claims, wherein the main shaft comprises one or more spline area(s) (14), the spline area(s) being adapted to be connected with the first end of the planetary gearing systems (11) of the energy-generating devices (9).

9. A wind turbine according to claim 8, wherein the spline area (14) is extending uninterrupted in an overall extension of the main shaft (7).

10. A wind turbine according to claim 8, wherein the spline areas (14) are arranged with predetermined distances along the main shaft (7).

11. A wind turbine according to claim 8, wherein the spline area (14) has an extension along the main shaft (7) which is larger than a connection area of the first end of the planetary gearing system.

12. A wind turbine according to any of the claims 10-11, wherein the spline areas have male splines arranged circumferentially around and in the longitudinal direction of the main shaft.

13. A wind turbine according to any of the claims 8-12, wherein the spline areas have a larger overall diameter than the rest of the main shaft. 14. A wind turbine according to claim 12, wherein the male splines in each spline area are tapered in the longitudinal extension, facilitating an inlet guide for the energy-generating devices when they are displaced along the main shaft.

15. A wind turbine according to any of the preceding claims, wherein one or more mating piece(s) is/are arranged between the energy-generating devices, the mating pieces being adapted to be part of a main shaft bearing adapted to support the main shaft so that the main shaft maintains its alignment in its longitudinal extension.

16. A wind turbine according to claim 15, wherein the mating piece has an inner diameter which is larger than the outer diameter of the main shaft. 17. A wind turbine according to according to claim 15, wherein the first end of the planetary gearing system has a mating piece with a female spline adapted to engage with the male spline of the main shaft to transfer torque from the main shaft to the planetary gearing system. 18. A wind turbine according to any of the preceding claims, wherein the planetary gearing system (11) comprises one or more epicyclical gear stages.

19. A wind turbine according to any of the preceding claims, wherein the energy-generating devices (9) comprise generators (25) and the hollow shaft is adapted to be a rotor of the generator.

20. A wind turbine according to any of the preceding claims, wherein the planetary gearing system is adapted to be disconnected from the hollow shaft of the energy-generating device to ensure that the main shaft rotation is not transferred to the hollow shaft when disconnected.

21. A wind turbine according to claim 15, wherein the mating piece of the first end of the planetary gearing system is displaceable on the spline area in a direction opposite the hollow shaft, enabling disconnection of the planetary gearing system from the hollow shaft.

22. A wind turbine according to any of the preceding claims, wherein the energy-generating devices are adapted to be independently set to idle. 23. A wind turbine according to any of the preceding claims, wherein the nacelle has a length, and the main shaft may extend more than 30% of the length of the nacelle, preferably more than 50%, more preferably more than 70%.

24. A wind turbine according to any of the preceding claims, wherein a main shaft bearing (18) is arranged at the end of the main shaft (7) opposite the hub.

25. A wind turbine according to any of the preceding claims, wherein additional main shaft bearings (19) are arranged along the main shaft (7). 26. A wind turbine according to any of the preceding claims, wherein one or more support elements (80) can be arranged along the main shaft (7) to support the main shaft (7) during exchange and/or maintenance of the energy-generating devices (9). 27. A wind turbine according to any of the preceding claims, wherein an additional energy-generating device is arranged in the nacelle as a spare part.

28. A wind turbine according to any of the preceding claims, wherein a rotor lock is arranged in the vicinity of the hub, adapted to mechanically lock the hub to avoid unintended rotation of the hub.

29. A wind turbine according to any of the preceding claims, wherein a transformer is arranged in the nacelle or the tower. 30. A wind turbine according to any of the preceding claims, wherein the energy-generating devices each are housed in a casing (65), the casings comprising an opening (60) through which the main shaft can extend uninterrupted. 31. A wind turbine according to claim 1, wherein the energy-generating devices (9) are hydraulic pumps.

32. A method for demounting an energy-generating device (9) from a main shaft (7) in a wind turbine (1) according to any of the preceding claims, comprising the steps of:

- stopping the rotation of the main shaft (7), - dismounting and removing a main shaft bearing (18) from the end of the main shaft,

- positioning a support element between a hub and the energy-generating device (9) nearest the end of the main shaft (7),

- dismounting the energy-generating device from the bottom frame,

- displacing the energy-generating device towards the end of the main shaft, and

- removing the energy-generating device from the main shaft.

33. A method according to claim 32, wherein the step of positioning a support element is performed by positioning the support element on a side of the energy- generating device, the side being opposite a second side of the energy- generating device facing the end of the main shaft.

Description:
A WIND TURBINE

Field of the invention

The present invention relates to a wind turbine comprising a hub with one or more rotor blades connected to the hub and a nacelle, the hub being connected with a main shaft arranged inside the nacelle. The present invention also relates to a method for demounting an energy-generating device from a main shaft in a wind turbine according to the present invention. Background art

Wind turbines are becoming larger and larger, which provides high loads and forces on the different wind turbine components, such as bearing and gear systems. Particularly, the gear system can be problematic, and the high loads and forces often result in wind turbines having long downtime periods due to maintenance and service of the gearboxes. From DE 297 06 980 Ul a wind turbine is known.

Due to the disadvantages of the gearboxes, the size of the wind turbines is limited and thereby the capacity of a specific wind turbine.

Summary of the invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved wind turbine where the overall downtime is reduced.

It is also an object of the present invention to provide a wind turbine whose size is not limited due to the drawbacks of the known gearbox systems.

It is furthermore an object of the present invention to provide a wind turbine wherein service and maintenance of the energy-generating devices are facilitated. The above objects, together with numerous other objects, advantages, and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a wind turbine comprising

- a hub with one or more rotor blades connected to the hub,

- a nacelle arranged on a tower,

- the hub being connected with a main shaft arranged inside the nacelle, the main shaft having an outer diameter and extending from the hub towards an end of the nacelle opposite the hub, and rotating with a first rotational velocity, and - a plurality of energy-generating devices each comprising a hollow shaft having an inner diameter and a planetary gearing system, the planetary gearing system being connected with the main shaft at a first end and with the hollow shaft at a second end,

wherein the plurality of energy-generating devices are arranged in succession of each other along the main shaft, and

the inner diameter of the hollow shafts being larger than the outer diameter of the main shaft, whereby the hollow shafts are arranged concentrically around the main shaft so that the energy-generating devices are all driven by the main shaft via the planetary gearing systems.

Additionally, a bottom frame may extend from the hub end of the nacelle towards the opposite end of the nacelle.

In an embodiment, the energy-generating devices may be releasably connected to the bottom frame.

Furthermore, the bottom frame may have at least the same extension as the main shaft. Moreover, the energy-generating devices may be connected to the bottom frame by means of bolts or similar connecting means.

Furthermore, the energy-generating devices may be adapted to be slid on and along the bottom frame.

Also, the bottom frame may comprise a set of rails arranged on each side of the main shaft and be adapted to slidably support the energy-generating devices. In addition, the energy-generating devices may comprise wheels or rollers adapted to slide or roll on the set of rails or the bottom frame.

Further, the bottom frame may be arranged in relation to the main shaft with the same distance along the extension of the main shaft.

The main shaft and the hollow shaft may fully or partly overlap.

The main shaft may comprise one or more spline area(s), the spline area(s) being adapted to be connected with the first end of the planetary gearing systems of the energy-generating devices.

In one embodiment, the spline area may be extending uninterrupted in an overall extension of the main shaft.

Also, the spline areas may be arranged with predetermined distances along the main shaft.

The spline area may have an extension along the main shaft which is larger than a connection area of the first end of the planetary gearing system.

Moreover, the spline areas may have male splines arranged circumferentially around and in the longitudinal direction of the main shaft. Further, the spline areas may have a larger overall diameter than the rest of the main shaft.

The male splines in each spline area may be tapered in the longitudinal extension, facilitating an inlet guide for the energy-generating devices when they are displaced along the main shaft.

In an embodiment, one or more mating piece(s) may be arranged between the energy-generating devices, the mating pieces being adapted to be part of a main shaft bearing adapted to support the main shaft so that the main shaft maintains its alignment in its longitudinal extension. Furthermore, the first end of the planetary gearing system may have a mating piece with a female spline adapted to engage with the male spline of the main shaft to transfer torque from the main shaft to the planetary gearing system. In addition, the mating piece may have an inner diameter which is larger than the outer diameter of the main shaft.

Also, the planetary gearing system may comprise one or more epicyclical gear stages.

Further, the energy-generating devices may comprise generators, and the hollow shaft may be adapted to be a rotor of the generator.

Additionally, the planetary gearing system may be adapted to be disconnected from the hollow shaft of the energy-generating device to ensure that the main shaft rotation is not transferred to the hollow shaft when disconnected.

Moreover, the mating piece of the first end of the planetary gearing system may be displaceable on the spline area in a direction opposite the hollow shaft, enabling disconnection of the planetary gearing system from the hollow shaft.

Furthermore, the energy-generating devices may be adapted to be independently set to idle. In one embodiment, the nacelle may have a length, and the main shaft may extend more than 30% of the length of the nacelle, preferably more than 50%, more preferably more than 70%.

In another embodiment, an overhung crane may be arranged at the top of the nacelle.

Furthermore, a main shaft bearing may be arranged at the end of the main shaft opposite the hub. Also, additional main shaft bearings may be arranged along the main shaft. Additionally, one or more support elements may be arranged along the main shaft to support the main shaft during exchange and/or maintenance of the energy-generating devices. Moreover, an additional energy-generating device may be arranged in the nacelle as a spare part.

In addition, the energy-generating device may be hydraulic pumps. Furthermore, the main shaft may be hollow.

Also, a rotor lock may be arranged in the vicinity of the hub, adapted to mechanically lock the hub to avoid unintended rotation of the hub. Additionally, a transformer may be arranged in the nacelle or the tower.

In an embodiment, the energy-generating devices may each be housed in a casing, the casings comprising an opening through which the main shaft can extend uninterrupted .

The present invention also relates to a method for demounting an energy- generating device from a main shaft in a wind turbine as described above, comprising the steps of:

- stopping the rotation of the main shaft,

- dismounting and removing a main shaft bearing from the end of the main shaft,

- positioning a support element between a hub and the energy-generating device nearest the end of the main shaft,

- dismounting the energy-generating device from the bottom frame,

- displacing the energy-generating device towards the end of the main shaft opposite the hub, and

- removing the energy-generating device from the main shaft.

The step of positioning a support element may further be to position the support element on a side of the energy-generating device, the side being opposite a second side of the energy-generating device facing the end of the main shaft. Brief description of the drawings

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

Fig. 1 shows a wind turbine positioned offshore,

Fig. 2 shows a nacelle in a side view disclosing wind turbine components according to the present invention,

Fig. 3 shows the nacelle of Fig. 2 in a top view,

Fig. 4 shows the main shaft having a plurality of spline areas,

Fig. 5 shows in an enlarged view a spline area having male splines,

Fig. 6 shows in an enlarged view an energy-generating device according to the invention,

Fig. 7 shows another embodiment of the main shaft having a spline area extending in the overall length of the main shaft,

Fig. 8 shows another embodiment of a nacelle in a side view with the main shaft of Fig. 7,

Fig. 9 shows one stage of the planetary gearing system seen from the hub end of the nacelle, Fig. 10 shows an energy-generating device in an end view,

Fig. 11 shows another embodiment of an energy-generating device in an end view, and Figs. 12a-12d show a sequence of demounting energy-generating devices from the main shaft. All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested. Detailed description of the invention

In Fig. 1, an offshore wind turbine 1 is shown. The wind turbine comprises a foundation 2, a tower 3, a nacelle 4, a hub 5 and rotor blades 6, the rotor blades 6 being mounted to the hub. The tower is arranged on the foundation and the nacelle is arranged on the tower. The hub is rotatably connected with the nacelle.

The wind turbine 1 shown in Fig. 1 is an upwind wind turbine, i.e. a wind turbine where the nacelle 4 is placed downwind from the wind turbine blades 6. However, the invention may also advantageously be implemented in a downwind wind turbine, i.e. a wind turbine where the nacelle is placed upwind from the wind turbine blades.

In Fig. 2, the nacelle 4 is shown in a side view disclosing the interior of the nacelle 4. The hub 5 is connected with a main shaft 7 arranged inside the nacelle 4. The main shaft 7 has an outer diameter and extends from the hub 5 towards an end 8 of the nacelle 4 opposite the hub 5, and rotates with a first rotational velocity.

A plurality of energy-generating devices 9 are arranged in the nacelle 4. In this embodiment, four energy-generating devices are arranged in succession of each other along the main shaft 7. In other embodiments, the nacelle may comprise another number of energy-generating devices, such as 2, 3, 5 or 6 energy- generating devices or an even higher number. The main shaft 7 extends continuously from the hub 5 towards the end 8 of the nacelle. By 'continuously' is meant that the main shaft 7 is preferably made in one piece, however, in some circumstances, it may comprise several pieces connected to form an uninterrupted shaft. The main shaft 7 rotates with the same rotational velocity along the entire length.

Furthermore, the energy-generating devices 9 each comprise a hollow shaft 10, here shown as dotted lines. The hollow shafts 10 have an inner diameter. The energy-generating devices 9 also comprise a planetary gearing system 11 which is connected with the main shaft 7 at a first end 12 and with the hollow shaft 10 at a second end 13. According to the inventive idea, the inner diameter of the hollow shafts 10 is larger than the outer diameter of the main shaft 7, whereby the hollow shafts 10 are arranged concentrically around the main shaft 7. In this way, the energy- generating devices 9 are all driven by the main shaft 7 via the planetary gearing systems 11.

In this embodiment, the planetary gearing systems 11 are arranged behind the hollow shafts 10, however, in other embodiments, they may be arranged in front of the hollow shafts 10. Additionally, the main shaft 7 comprises a plurality of spline areas 14 arranged with predetermined distances along the main shaft 7, each spline area 14 being adapted to be connected with the first end 12 of the planetary gearing system 11. Near the bottom of the nacelle 4, a bottom frame 15 extends from the hub end

16 of the nacelle 4 towards the opposite end 8 of the nacelle 4. The bottom frame is adapted to support the different wind turbine components arranged inside the nacelle and to support the floor arranged in the nacelle, enabling service personnel to move around safely in the nacelle. The bottom frame 15 is also adapted to absorb any forces and loads generated by the rotor blades and to lead these forces and loads to the tower via the yawing system (not shown).

The bottom frame 15 has at least the same extension as the main shaft 7, and as shown in Fig. 2, it may also exceed the extension of the main shaft 7.

The bottom frame 15 may also support (not shown) an overhung crane system

17 arranged at the top of the nacelle 4. The overhung crane system 17 may assist in handling the different wind turbine components during maintenance, service and replacement.

At the end of the main shaft 7, a main shaft bearing 18 is arranged opposite the hub for supporting the main shaft 7 and ensuring proper alignment of the main shaft 7 along its extension. Furthermore, additional main shaft bearings may be arranged along the main shaft 7. In the embodiment shown in Fig. 2, one additional main shaft bearing 19 is arranged between the second and third energy-generating devices.

Furthermore, each energy-generating device 9 comprises a monitoring system 46 which monitors the status of the device and is connected with a control system 47 adapted to disconnect the device 9 automatically if the monitoring system detects problems with the device 9. In this way, the wind turbine is still able to produce energy until the device 9 can be serviced or replaced.

In Fig. 3, the nacelle 4 is shown in a top view. The energy-generating devices 9 are supported by the bottom frame 15. Furthermore, the bottom frame 15 comprises at least two longitudinal frames extending in the length direction of the nacelle, and the longitudinal frames are connected by transverse beams.

It is within the inventive idea that a plurality of energy-generating devices 9 are driven by the same main shaft 7 so that the wind turbine 1 may have a high capacity, e.g. more than 8 MW, even higher than 15 MW, in circumstances where the energy-generating devices are generators while at the same time having a high producing time. This is due to the fact that the wind turbine 1 is able to produce energy even though one or more of the energy-generating devices 9 is/are down for service or have been damaged . It is therefore preferable, that the main shaft 7 extends more than 30% of the length of the nacelle, preferably more than 50%, more preferably more that 70% so that a plurality of energy-generating devices 9 may be arranged in succession of each other. In Fig. 4, a part of one embodiment of the main shaft 7 is shown. The spline area 14 has an extension I along the main shaft 7 which is larger than a connection area of the first end of the planetary gearing system. This will be further described in connection with Fig. 6. Furthermore, the spline areas 14 have male splines 20 arranged circumferentially around and in the longitudinal direction of the main shaft 7, and the spline areas 14 have an overall diameter d s which is larger than the outer diameter d 0 of the main shaft 7. In this embodiment, the inner diameter of the hollow shafts is larger than the overall diameter d s .

In Fig. 5, an enlarged view of a spline area 14 of the main shaft 7 is shown. The male splines 20 are each tapered towards their ends 120, 121. Hereby it is obtained that when the energy-generating devices 9 with the mating pieces of the planetary gearing system are displaced along the extension of the main shaft, the tapered ends 120, 121 of the male splines 20 will function as guides for the female splines, if they have rotated slightly in an area of the main shaft without a spline area, of the mating pieces, whereby displacement of the devices along the extension of the main shaft is facilitated.

In Fig. 6, an enlarged, partly sectional view of an energy-generating device 9 is shown. In this embodiment, the energy-generating device 9 comprises a generator 25, and the hollow shaft 10 is the rotor of the generator 25.

The planetary gearing system 11 is in this embodiment shown with one stage, however, in other embodiments, the planetary gearing system 11 may comprise a plurality of stages to ensure that the desired rotational velocity of the hollow shaft 10 is obtained.

The first end 12 of the planetary gearing system 11 has a mating piece with a female spline (not shown) adapted to engage with the male spline 20 of spline area 14 of the main shaft 7 to transfer torque from the main shaft 7 to the planetary gearing system 11. The design of the planetary gearing system 11 will be described in more detail in connection with Fig. 9.

The mating piece has an inner diameter which is larger than the outer diameter do of the main shaft 7. As described above, the hollow shaft 10 has an inner diameter d, which is also larger than the outer diameter d 0 of the main shaft 7. Hereby, it is obtained that the energy-generating device 9, when disconnected from the bottom frame 15, may be slid along the extension of the main shaft 7 without touching the main shaft 7, facilitating replacement for service and maintenance. This will be further described below.

The generator 25 comprises a stator 26, and the hollow shaft 10, i.e. the rotor of the generator, may be positioned by bearings 27 arranged on each side of the rotor in such a way that a radial air gap 28 is maintained between the rotor and stator of the generator.

In circumstances where one of the energy-generating devices 9 does not function properly, it may be desirable to disengage the energy-generating device 9 until it can be serviced. The planetary gearing system 11 may be adapted to be disconnected from the hollow shaft 10 of the energy-generating device 9 to ensure that the rotation of the main shaft 7 is not transferred to the hollow shaft 10.

As described above, the spline area 14 has an extension I along the main shaft 7 which is larger than a connection area 30 of the first end 12 of the planetary gearing system 11. The mating piece or the connection area 30 of the first end 12 of the planetary gearing system 11 may be displaceable on the spline area 14 in a direction A opposite the hollow shaft 10, enabling disconnection of the planetary gearing system 11 from the hollow shaft 10 to ensure that the rotation of the main shaft 7 is not transferred to the hollow shaft 10. Hereby, the energy- generating device 9 is disconnected. However, even though one energy- generating device is disconnected, the wind turbine may still produce energy, nevertheless at a lower capacity than intended, whereby the total yield of the wind turbine will be higher over time due to the low downtime of the wind turbine.

In Fig. 7, another embodiment of the main shaft 7 is shown. The main shaft 7 has, in this embodiment, a spline area 14, which is extending uninterrupted in an overall extension of the main shaft 7. The male splines 20 are thus all extending along the main shaft 7. Due to this design of the main shaft 7, the different energy-generating devices 9 may easily be displaced along the main shaft without any risk that the mating piece will rotate, since the female splines of the mating piece will always mate with the male splines 20 of the spline area 14 of the main shaft 7.

This design provides the further advantage that the energy-generating devices may be positioned with the same or a varying distance between them along the main shaft 7 and in a varying number of energy-generating devices from wind turbine to wind turbine as long as there is space along the main shaft. Further, the present invention makes it possible to have standard-sized components, i.e. nacelle length/width, main shaft length, size and capacity of energy-generating devices, etc., whereby each wind turbine may be equipped with the number of energy-generating devices which are optimal in view of the geographical position of the wind turbine and the desired capacity.

Fig. 8 shows, in the same manner as Fig. 2, a nacelle 4 having a main shaft 7 with only one spline area 14 extending in the entire length of the main shaft, so that displacement of the energy-generating devices is facilitated.

When the spline area 14 is extending in the entire length of the main shaft as shown in Figs. 7 and 8, one or more mating piece(s) (not shown) may be arranged between energy-generating devices 9, the mating pieces being adapted to be part of a main shaft bearing 18, 19 adapted to support the main shaft 7 so that the main shaft 7 maintains its alignment in its longitudinal extension.

In Fig. 9, one stage of the planetary gearing system is seen from the hub end of the nacelle. The main shaft 7 has the smallest diameter and is placed nearest the centre of the planetary gear stage. The male spline 20 of the spline area 14 of the main shaft 7 meshes with the female spline which is connected with an outer annulus gear part 40, thus having the same rotation as the main shaft 7. The outer annulus gear part 40 meshes with the planet gear parts 41. The planet gear parts 41 are rotated around shafts 42 which are connected to a stationary part (not shown). The planet gear parts 41 again meshes with the hollow shaft 10, whereby the hollow shaft rotates with a higher rotational velocity than the main shaft 7. As mentioned above, the planetary gearing system 11 may comprise several stages.

In Fig. 10, an energy-generating device 9 is shown in an end view, e.g . from the hub end. The energy-generating device 9 is housed in a casing 65, the casing 65 comprising an opening 60 through which the main shaft 7 can extend uninterrupted. As mentioned above, the energy-generating device 9 is supported by the bottom frame 15 and is releasably connected with the bottom frame 15. The energy-generating device 9 may be connected with the bottom frame 15, e.g. by means of bolts 70 or similar connecting means, ensuring that the energy- generating device 9 is maintained in position during operation to secure alignment of the main shaft 7 and the hollow shaft 10. In Fig. 11, the energy-generating device 9 comprises a set of wheels 75 or rollers, arranged between the device and the bottom frame 15, enabling the device 9 to be rolled or slid along the bottom frame 15 when the bolts 70 have been released and moved.

In one embodiment, the bottom frame 15 may comprise a set of rails arranged on each side of the main shaft 7 and adapted to slidably support the energy- generating devices 9. Preferably, the bottom frame 15 is arranged in relation to the main shaft 7 with the same distance along the extension of the main shaft 7 to facilitate displacement of the energy-generating devices along the main shaft.

Furthermore, the energy-generating devices may comprises brakes, so that when one or more of the energy-generating devices have been released from the bottom frame or rails of the bottom frame, the movement of the energy- generating device along the bottom frame may be controlled. This is especially expedient in circumstances where the bottom frame is inclined.

In another embodiment, the energy-generating devices may be displaced by means of the overhung crane. Furthermore, the overhung crane may also be arranged in a way that enables it to lower and hoist wind turbine components, such as energy-generating devices, down from or up to the nacelle.

In circumstances where one or more energy-generating devices are to be replaced, one or more support elements can be arranged along the main shaft 7 to support the main shaft 7 during exchange and/or maintenance of the energy- generating devices 9.

This may be performed by first stopping the rotor blades and then locking the hub by means of a rotor lock to secure that no unintended movement of the rotor blades occurs. Hereinafter, the one or more support elements is/are arranged between the energy-generating devices 9.

In Figs. 12a to 12d, a sequence of dismounting and displacing energy-generating devices 9 is shown schematically. After the rotor lock has been activated, the main shaft bearing 18 is then dismounted from the main shaft 7. In Fig. 12a, the main shaft bearing has already been removed. Hereinafter, a support element 80 is arranged between the third and fourth energy-generating devices 9 seen from the left side of Fig. 12b, and subsequently, the energy-generating device nearest the end of the main shaft 7, i.e. the fourth from the left side of Fig. 12b, is disconnected and subsequently displaced along the main shaft until it is free of the main shaft 7 as indicated by arrow B.

Subsequently, a support element 80 is mounted at the end of the main shaft 7 to support and maintain the alignment of the main shaft as shown in Fig. 12c. A support element 80 is also arranged between the second and third energy- generating devices 9 seen from the left side of Fig. 12c, and subsequently, the energy-generating device nearest the end of the main shaft 7, i.e. the third from the left side of Fig. 12b, is disconnected and subsequently displaced along the main shaft as indicated by arrow B until it reaches the end of the main shaft 7. Then, the support element 80 at the end of the main shaft 7 is moved to the other side of the energy-generating device as shown in Fig. 12d, whereby it supports the main shaft 7 at the end as the energy-generating device is being displaced along the main shaft until it is free of the main shaft 7 as indicated by arrow B.

This procedure may be repeated until all the energy-generating devices have been displaced and may be applied mutadis mutandis when the energy- generating devices are to be mounted and positioned on the main shaft 7 again. Furthermore, an additional energy-generating device may be arranged in the nacelle as a spare part to facilitate rapid replacement of a malfunctioning energy- generating device.

The present invention has mainly been described in connection with energy- generating devices comprising a generator, however, within the inventive idea, the energy-generating devices may also comprise hydraulic pumps. In this embodiment, the design is substantially the same since the hollow shafts drive the hydraulic pumps. The hydraulic fluid may be led down through the tower and may e.g. be used for powering a generator or other units. Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.




 
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