WO2001094779A1

WO2001094779A1 - A power generating device

Info

Publication number: WO2001094779A1
Application number: PCT/SE2001/001218
Authority: WO
Inventors: Marco Sipi
Original assignee: ABB AB
Current assignee: ABB AB
Priority date: 2000-06-06
Filing date: 2001-05-31
Publication date: 2001-12-13
Anticipated expiration: 2002-12-06
Also published as: SE0002092L; AU2001266451A1; SE0002092D0

Abstract

A power generating device comprising a turbine (1) and a generator with a rotor and a stator, which stator (3) is connected to a support arrangement (7), a hub (15) of the turbine being connected to the rotor (4) by means of a connecting arrangement adapted to transmit a turning moment from the hub to the rotor. The connecting arrangement comprises an axle (8) rotatably mounted relative to the stator, the hub (15) of the turbine and the rotor (4) being connected to said axle (8) and being arranged at a distance from each other as seen in the longitudinal direction of the axle. The axle (8) is adapted to transmit the turning moment from the turbine hub (15) to the rotor (4) without or with only insignificant simultaneous transmission of bending movements.

Description

A power generating device

FIELD OF THE INVENTION AND PRIOR ART

The present invention relates to a power generating device according to the preamble of the subsequent claim 1. It is pre- ferred that the turbine is a wind power turbine, i.e. that the device is suitable for a wind power plant. In particular, relatively high efficient devices with output powers up to several megawatts are intended in that connection.

DE C2 44 02 184 discloses a power generating device with a rotor driven by a turbine according to the preamble of the subsequent claim 1. In connection with this known device, it is suggested that the turbine hub is fastened to the rotor in such a way that the turbine hub will be carried by the rotor. The turbine hub protrudes in a cantilever manner from the rotor, which is mounted in bearings relative to the stator. The turbine hub carries wings, which have a considerable size, and will consequently be subjected to large forces. In particular, these forces result in that the rotor will be subjected to considerable bending deformations, which is accentuated by the cantilever design of the turbine hub from the rotor. There is a risk of these bending deformations influencing the constancy of the air gap between the stator and the rotor of the generator. In order to counteract this at the known device, it is required a very heavily dimen- sioned carrying centre pin and hub and the corresponding also applies to the bearing/bearings between the rotor and the stator. This implies in its turn an increased weight of the mechanically supporting parts and a more costly design of the bearing/bearings.

Known designs of power generating devices also include directly driven generators where a turbine is connected to the rotor of the generator via a turning moment transmitting axle, the axle being mounted in bearings in relation to a supporting arrangement via a bearing arranged in the vicinity of the turbine and a bearing arranged in the vicinity of the rotor. The above described problems with influence on the air gap between the rotor and the stator due to bending deformations of the axle caused by the forces exerted on the turbine hub arise also here when the turbine is of a large size and a large weight.

OBJECT OF THE INVENTION

The object of the present invention is to develop the device according to the preamble of claim 1 further so that bending mo- ments from the turbine hub, in a manner which is advantageous as concerns the load, can be carried by the device without the bending moments to an unacceptable negative extent causing an influence on the air gap between the rotor and the stator of the generator.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved in that the connecting arrangement comprises an axle rotatably mounted relative to the stator, the hub of the turbine and the rotor being connected to said axle and being arranged at a distance from each other as seen in the longitudinal direction of the axle, and that the axle is adapted to transmit the turning moment from the turbine hub to the rotor without or with only insignificant simul- taneous transmission of bending movements. This solution implies, as the rotor is being released from bending movements, that the risk of undesired variations of the air gap between the rotor and the stator is substantially reduced and that the mechanically supporting parts can be dimensioned as less heavy than what would have been the case if bending moments from the turbine hub directly could have caused bending deformations in the rotor. The solution to the problem will also in broad result in a more rugged and reliable design in the sense that the risk of loads negatively influencing the generator in its entirety via the turbine hub is considerably reduced. Furthermore, the solution makes it possible to essentially reduce the influence on the air gap caused by bearing slackness.

According to a first preferred embodiment of the invention, the device comprises two bearing units, by means of which the axle is rotatably mounted relative to the supporting arrangement and the stator. A first of these bearing units is arranged at a first section of the axle and is adapted to allow transmission of bending movements in the axle from one side of this first bear- ing unit to the other side thereof as seen in the longitudinal direction of the axle, whereas a second of these bearing units is arranged at a second section of the axle between the first axle section and the rotor and is adapted not to, or to only to an insignificant extent, allow transmission of bending movements in the axle from one side of the second bearing unit to the other side thereof as seen in the longitudinal direction of the axle. Stressings on the axle as a consequence of bending moments generated by the turbine hub will thereby be carried by the axle itself, without influencing the rotor, and be transmitted to the support arrangement. As a consequence of the rotor of the generator in the main not being subjected to bending movements, there will in the main not occur any variations as regards the working relation between stator and rotor. By the so-called inner ring rotation, this embodiment also has advantages concerning maintenance, lifetime etc. According to a second preferred embodiment of the invention, the rotor is rotatably mounted to the support arrangement or to an element connected to the support arrangement, the connecting arrangement further comprising one or several connecting members connecting the axle to the rotor, which connecting members are adapted to transmit the turning moment from the axle to the rotor without or with only insignificant simultaneous transmission of bending movements. The connecting members are suitably torsion stiff but yielding to bending moments, the yieldingness can be realized through the elasticity of the connecting members. This embodiment also has the above-described advantages concerning reduction of the influence on the generator by the bending moment.

An embodiment advantageous from a constructional and assembling point of view implies that the axle comprises a first axle , part to which the turbine hub is fixed and a second axle part to which the rotor is fixed, a coupling device being arranged to transmit turning moments from the first axle part to the second axle part. Consequently, the first axle part with associated turbine hub and the second axle part with associated rotor can each form a premade unit, which is completely prepared in factory conditions, whereafter the axle parts are connected to each other in the support arrangement at the occasion for the instal- lation. Preferably, also the stator is fixed to the second axle part so that the entire generator together with the second axle part can form a premade unit, which is completely prepared in factory conditions. In this way, the stator and the rotor can be assembled and position adjusted in relation to each other in fac- tory conditions, which makes it easier to obtain a uniform and narrow air gap between the rotor and the stator all around.

According to a particularly preferred embodiment of the invention, the coupling device constitutes a releasable flange cou- pling, a holding member being arranged to co-operate with at least the flange of one of the axle parts so as to hold this axle part in its position also after the two axle parts have been released from each other. In this way, it will in a simple manner be possible to release the two axle parts from each other so that one of or both axle parts with associated turbine/generator can be released from the support arrangement for exchange or maintenance work.

In a particularly advantageous embodiment of the device, the rotor is provided with permanent magnets.

Further features and advantages of the inventional device will appear from independent claims and the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the enclosed drawings, a more specific description of embodiment examples of the invention will follow hereinbelow.

In the drawings:

Fig 1 is a schematic, partly cut sectional view of the inventional device as seen horizontally from one side, the support arrangement included in the device being connected to a tower or a mast,

Fig 2 is a cut along A-A in Fig 1 , illustrating a holding member included in an embodiment of the device according to the invention,

Fig 3 is a schematic, cut sectional view of a rotor and stator included in the device according to the invention, which rotor and stator are fixed to an axle part according to a first alternative, and Fig 4 is a schematic, cut sectional view of a rotor and stator included in the device according to the invention, which rotor and stator are fixed to and an axle part according to a second alternative.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig 1 illustrates the power generating device as comprising a turbine, generally denoted as 1 , and a generator 2 with a stator 3 and a rotor 4. The stator 3 has a ring-shaped element 5, which for instance by means of a flange joint 6 is fixed to a support arrangement 7, which here has the character of an axle housing, whereas the rotor 4 for instance by means of shrinkage fit is fixed to an axle 8 extending through the support arrangement 7.

In the embodiment shown in Fig 1 , the device is included in a wind power plant, the support arrangement 7 being connected to a tower or a mast via a rotary bearing 9, the upper part of said tower or mast being denoted as 10 in Fig 1. The support ar- rangement 7 forms a part of a tower head 1 1 and by means of said rotory bearing 9 the support arrangement 7, and thereby the entire tower head 1 1 , can be rotated relative to the tower 10. \n the tower head 1 one or several coolers, generally indicated at 12 in Fig 1 , can be arranged adjacent to the generator 2.

The stator 3 has stator elements, schematically indicated at 13 in Figs 3 and 4, intended for magnetical co-operation with permanent magnets in the rotor 4. These stator elements comprise stator windings with a suitable core arrangement and optionally stator plates facing the periphery of the rotor.

The rotor 4 has permanent magnets, not shown, which according to a preferred alternative co-operate in a conventional manner with flux-concentrating members distributed along the cir- cumference of the rotor. Between the stator elements of the stator and the flux-concentrating members of the rotor there is an air gap 14, see Fig 3, which is to be maintained constant as far as possible. It is emphasized that it is also possible to design the rotor in such a way that the permanent magnets will be located radially outside the stator elements. According to an al- ternative embodiment, the rotor is provided with surface mounted permanent magnets and the air gap is formed between the permanent magnets and the stator elements.

The turbine 1 has a hub 15 and turbine wings 16 fixed on the hub in a suitable manner. The hub 15 is fixed to a first end 17 of the axle 8 extending through the support arrangement 7, which axle is carrying the rotor 4 at its other end 18. Near to its first end 17, the axle 8 is rotatably mounted to the support arrangement 7 via a first bearing unit 19, and the turbine 1 is conse- quently rotatable relative to the tower head 1 1. Near to its second end 18, at an axle section located in front of the axle section to which the rotor is fixed, as seen in a direction along the axle 8 from the first end 17 towards the second end 18, the axle 8 is rotatably mounted to the stator 3 via a second bearing unit, which in the example shown comprises two separate bearings 20, 21. The axle 8 constitutes a connecting arrangement adapted to transmit turning moments from the hub 15 to the rotor 4. Turning moments here refer to such influence that sets the rotor in pure rotation around its rotation axis. ^;

The bearing unit 19 arranged at the first end of the rotor 17, henceforth denominated the first bearing unit, is adapted to allow transmission of bending movements in the axle 8 from one side of the bearing unit 19 to the other side thereof as seen in the longitudinal direction of the axle. For this purpose, the bearing unit 19 suitably consists of a self-aligning roller bearing.

The bearing unit 20, 21 arranged at the second end 18 of the axle, henceforth denominated the second bearing unit, is how- ever adapted not to, or to only to an insignificant extent, allow transmission of bending movements in the axle 8 from one side of the bearing unit 20, 21 to the other side thereof as seen in the longitudinal direction of the axle. For this purpose, this bearing unit suitably comprises two separate bearings 20, 21 arranged at a distance from each other as seen in the longitudi- nal direction of the axle, which bearings for instance can be roller bearings. It is emphasized that the second bearing unit also can comprise more than two separate bearings and that it can consist of one single bearing of suitable design as well. The principle thing is that the second bearing unit prevents or es- sentially prevents bending movements in the axle 8 from being transmitted from the forward part of the axle 8 to the axle section to which the rotor 4 is fixed. This can for instance be achieved by means of a slide bearing having a certain axial extension. It is also possible to make the second bearing unit comprise roller bearings as well as slide bearings.

Consequently, this implies that when the axle 8 is subjected to bending, as a consequence of the load from the turbine 1 , the arising bending movements will not be transmitted to the rotor 4, at least not to any appreciable extent, so that the rotor 4 consequently will not be subjected to any detrimentally deforming or otherwise position altering influence as a consequence of the deflection of the axle 8. Such deformations or position alterations of the rotor 4 that causes alterations of the air gap 14 be- tween the rotor 4 and the stator 3 are particularly to be avoided in this respect.

According to a preferred embodiment of the device according to the invention, the axle comprises two separate axle parts, namely a first axle part 22, to which the turbine hub 15 is fixed, and a second axle part 23, to which the generator 2 is fixed, a coupling device 24 being arranged to transmit turning moment from the first axle part 22 to the second axle part 23. The first axle part 22 is rotatably mounted to the support arrangement 7 by means of the first bearing unit 19, and the second axle part 23 is rotatably mounted to the stator 3 by means of the second bearing unit 20, 21 . In order to facilitate the assembly and disassembly of the turbine 1 , it is suitable, as shown in Fig 1 , to make the support arrangement 7 comprise two parts 7a, 7b, which are fixed to each other for instance by means of a flange joint, the first axle part 22 being fixed to the forward one 7a of these two parts via the first bearing unit 19.

The coupling device 24 for connecting the axle part 22, 23, suitably consists of a flange coupling, the first and second axle part 22, 23 each being provided with a flange 25, 26, the flanges of the two axle parts being intended to be coupled together. The flanges 25, 26 can for instance be releasably fixed relative to each other by means of fixing elements such as screws or bolts. In the embodiment according to Fig 2, the flanges 25, 26 are provided with axial through holes 27 for bolts to pass.

In order to facilitate the release of the axle parts 22, 23 from each other, a holding member 28 can be arranged to co-operate with at least the flange 25 of one of the axle parts so as to hold this axle part 22 in its position also after the two axle parts 22, 23 have been released from each other. In the embodiment shown in Figs 1 and 2, this holding member 28 comprises two locking elements 29 in the form of wedges, each of which being attached to its own holder 30. The holders 30 are arranged on opposite sides of the axle and are fixedly connected to the support arrangement 7. The locking elements 29 are here adapted to co-operate with a ring-shaped groove 31 extending along the periphery of the flange 25 of the first axle part. The holding member 28 further comprises suitable means, not shown, for displacing the locking elements 29 in radial direction down into and out of said groove 31. During the normal operation of the device, there is a certain clearance between the locking elements 29 and the groove 31 so that the locking elements 29 will not be in contact with the flange 25. In this connection, the locking elements 29 are, however, protruding so far that they extend down into the groove 31 of the flange. The locking ele- ments 29 hereby, in co-operation with the groove 31 , lock the axle 8 from axial displacement. A holding member of the kind in question can also be arranged at the flange 26 of the second axle part 23. In order to obtain a good contact between the respective locking element 29 and the co-operating flange 25, when these come into engagement with each other, the locking elements 29 are provided with an arched surface facing the flange 25, the curvature of which surface approximately corresponds to the curvature of the bottom surface of the groove.

In the embodiment described with reference to Figs 1 and 2, the coupling device 24 is placed between the first bearing unit 19 and the second bearing unit 20, 21 . According to a not shown variant of the inventional device, the second bearing unit com- prises three separate bearings, two of the bearings being arranged on the side of the coupling device 24 turned away from the hub, i.e. on the second axle part 23, whereas the third bearing in the second bearing unit is arranged on the side of the coupling device 24 turned towards the hub, i.e. between the coupling device 24 and the first bearing unit 19. According to this variant, the coupling device 24 is consequently arranged between two separate bearings included in the second bearing unit.

According to a particularly preferred embodiment of the invention, the coupling device 24 is flexible so that it transmits turning moments from the first axle part 22 to the second axle part 23 without or with only insignificant simultaneous transmission of bending movements.

In the embodiment described with reference to Figs 1 and 2, the bearings 20, 21 included in the second bearing unit have been arranged to mount the axle 8 to the stator 3. However, it is also possible to let the axle 8 be mounted in bearings directly to a part of the support arrangement 7 via the bearings 20, 21 of the second bearing unit, in which case the stator 4 is fixed to the support arrangement 7, for instance by means of shrinkage fit, without being in direct contact with said bearings 20, 21.

In Figs 3 and 4, two different alternatives for the mounting of the rotor 4 and the stator 3 to the second axle part 23 are shown. It is emphasized that the shown mounting alternatives are also usable when the axle 8 is formed in one single piece. The alternative shown in Fig 3 corresponds to what has already been described with reference to the embodiment according to Fig 1 , and this will therefore not be further commented on here.

According to the alternative shown in Fig 4, the rotor 4 is rotatably mounted to the ring-shaped element 5 of the stator by means - of at least one bearing 32, which element here has the shape of a sleeve with a flange 33 intended for attachment to the support arrangement 7. The second axle part 23 extends through the inner cavity of the ring-shaped element 5, which second axle part at one of its ends is provided with the flange 26 intended for connection to the first axle part 22. At its other end the axle part 23 is connected with the rotor 3 via one or several turning moment transmitting connecting members 34. In this case, these connecting members 34 are together with the axle 8 included in a connecting arrangement adapted for transmission of turning moment from the hub 15 to the rotor 4. In the shown example, the connecting members are at a first end fixed to the axle part 23 and at a second end fixed to the rotor 4. The external diameter of the axle part is smaller than the internal diameter of the ring-shaped element so that the axle part 23 can rotate - within the element 5 without being in contact with this element.

The connecting members 34 included in the connecting arrangement are torsion stiff in the sense that they are capable of transmitting turning moments between the turbine hub 15 and the rotor 4, but yielding to bending moment. Within the scope of these general directions the average man skilled in the art realizes that many possibilities of realization are offered. Here a couple of alternatives may be discussed only for the purpose of exemplification.

According to a variant, the yieldingness of the connecting mem- bers 34 could be realized in that these are elastic. The elasticity is in this case to be such that it does not negatively affect the turning moment transmission, but this elasticity shall, however, allow the connecting members 34 to deform with a relatively small resistance when influenced by bending movements so that these are not, or only to an insignificant extent, transmitted to the rotor 4.

The connecting member 34 could be realized in the form of an annularly continuous structure, possibly provided with longitudi- nal slits facilitating elastic deformation under the influence of bending movements, but they could also be realized in the form of several separate connecting members distributed around the axle. Besides, these can be connected to the axle part 23 and the rotor 4, respectively, via suitable releasable fixing elements, such as screws or bolts or the like.

The device according to the invention can also comprise a brake device so as to, when so required, brake or completely stop the rotation of the turbine 1 and the axle 8 connected thereto. This braking device is suitably arranged in the support arrangement 7 and can for instance consist of a disc brake, generally indicated at 35 in Fig 1 .

The inventional device comprises units that can be assembled in a factory, the generator 2 and the turbine hub 15 being applied to its own separate axle part 22, 23. These units can thereafter be transported to the intended place of application, where the axle parts 22, 23 are mounted to the support arrangement 7 and connected to each other by means of the coupling device. Such a procedure eliminates the need of troublesome assembly of parts at the intended place of application. It is realized that the flanges 25, 26 of the axle parts are to have such a size that they can be inserted through intended insert openings in the support arrangement 7 so as to be connected together.

Owing the fact that the turbine 1 and the generator 2, as described above, are arranged at different ends of a turning moment transmitting axle 8, it will be possible to obtain a location of the turbine 1 and the generator 2 very favourable in several aspects. Inter alia, the static load on the tower head can be bal- anced by locating the turbine 1 and the generator at different ends of the tower head. Furthermore, the generator 2 as well as the turbine 1 will be easily accessible for repair and maintenance through such a location. The free space obtained between the turbine 1 and the generator 2 can be used for in- stance as a switch gear and control equipment room. A further advantage of locating the generator 2 at a distance from the turbine 1 is that the area directly behind the turbine blades 16 will be free, whereby this part of the tower head can be designed for the achievement of optimal flow conditions around the turbine hub 15 and the turbine blades 16. In the embodiment shown in Fig 1 , the tower head 1 1 has been made arrow-shaped, the turbine hub 15 being included in a forward part of the tower head 1 1 , which part is shaped like an arrow point. In this way, the turbine blades 16 will be open against the wind along the whole length of the turbine blades, which has a favourable influence on the driving power of the turbine.

It is evident that the described device can be modified in several ways within the scope of the inventional idea here referred to. What is here presented should thus only be considered as examples of realization of the invention. Within the scope of the inventional idea all the variants falling within the scope of the subsequent claims are embraced and also equivalent embodiments. It is pointed out that the inventional power generating device realized as a wind power plant with advantage can be included in a larger wind power park comprising one or several wind power plants preferably of the same but also of other design. In a practical realization it is preferred that the generator included in the device is intended for a voltage exceeding 10 kV, preferably 16-30 kV, and has a power suitably larger than 1 MW, preferably between 1 ,5 and 6 MW. Such a generator is preferably provided with a stator having stator windings designed as described in WO99/29025 A1 , where the winding encloses the electric field. The weight of the rotor can here be between 10 and 150 tons.

Claims

1. A power generating device comprising a turbine (1 ) and a generator (2) with a rotor (4) and a stator (3), which stator (3) is connected to a support arrangement (7), a hub (15) of the turbine being connected to the rotor (4) by means of a connecting arrangement adapted to transmit a turning moment from the hub to the rotor, characterized in that the connecting arrangement comprises an axle (8) rotatably mounted relative to the stator (3), the hub (15) of the turbine and the rotor (4) being connected to said axle (8) and being arranged at a distance from each other as seen in the longitudinal direction of the axle, and that the axle (8) is adapted to transmit a turning moment from the turbine hub (15) to the rotor (4) without or with only insignificant simultaneous transmission of bending movements.

2. A device according to claim 1 , characterized in that the device comprises two bearing units (19; 20, 21 ), by means of which the axle (8) is rotatably mounted relative to the support arrangement (7) and the stator (4), that a first (19) of these bearing units is arranged at a first section (17) of the axle (8) and is adapted to allow transmission of bending movements in the axle (8) from one side of the bearing unit (19) to the other- side thereof as seen in the longitudinal direction of the axle, and that a second (20, 21 ) of these bearing units is arranged at a second section (18) of the axle (8) between the first axle section (17) and the rotor (4) and is adapted not to, or to only to an insignificant extent, allow transmission of bending movements in the axle (8) from one side of the bearing unit (20, 21 ) to the other side thereof as seen in the longitudinal direction of the axle.

3. A device according to claim 2, characterized in that the first bearing unit consists of a self-aligning roller bearing (19).

4. A device according to claim 2 or 3, characterized in that the second bearing unit comprises at least two separate bearings (20, 21 ) arranged at a distance from each other as seen in the longitudinal direction of the axle.

5. A device according to any of claims 2-4, characterized in that the second bearing unit comprises a slide bearing.

6. A device according to claim 1 , characterized in that the rotor (4) is rotatably mounted to the support arrangement (7) or to an element (31 ) connected to the support arrangement, that the connecting arrangement further comprises one or several connecting members (34), which connect the axle (8) to the rotor (4), each connecting member (34) being adapted to transmit the turning moment from the axle (8) to the rotor (4) without or with only insignificant simultaneous transmission of bending movements.

7. A device according to claim 6, characterized in that each connecting member (34) is torsion stiff but yielding to bending moments.

8. A device according to claim 7, characterized in that the yieldingness of the respective connecting member (34) is elas- tic.

9. A device according to any of the preceding claims, characterized in that the axle (8) comprises a first axle part (22), to which the turbine hub (15) is fixed, and a second axle part (23), to which the rotor (4) is fixed, and that the device further comprises, a coupling device (24) adapted to transmit turning moments from the first axle part (22) to the second axle part (23).

10. A device according to claim 9, characterized in that the coupling device (24) is adapted to transmit turning moments from the first axle part (22) to the second axle part (23) without or with only insignificant simultaneous transmission of bending movements.

1 1 . A device according to claim 9 or 10 in combination with any of claims 2-5, characterized in that the first axle part (22) is rotatably mounted to the support arrangement (7) via the first bearing unit (19), and that the second axle part (23) is rotatably mounted to the support arrangement (7) or the stator (4) via the second bearing unit (20, 21 ).

12. A device according to claim 9 or 10 in combination with any of claims 2-5, characterized in that the coupling device (24) is arranged between two separate bearings included in the second bearing unit (20, 21 ).

13. A device according to any of claims 9, 1 1 and 12, characterized in that the coupling device constitutes a flange coupling (24), the first and second axle parts (22, 23) each being provided with a flange (25, 26), the flanges of the first and second axle parts being intended to be connected to each other.

14. A device according to claim 13, characterized in that a holding member (28) is adapted to co-operate with at least the flange (25) of one of the axle parts so as to hold this axle part (22) in its position also after the two axle parts (22, 23) have been released from each other.

15. A device according to claim 14, characterized in that the holding member (28) comprises at least one locking element (29), which is connected to the support arrangement (7) and can be arranged to extend down into a groove (31 ) arranged along the periphery of the flange (25) co-operating with the holding member (28).

16. A device according to any of the preceding claims, characterized in that the turbine (1 ) is a wind power turbine.

17. A device according to any of the preceding claims, characterized in that the rotor (3) is provided with flux generating permanent magnets.

18. A wind power unit, characterized in that it comprises a power generating device according to any of the preceding claims.

19. A wind power unit according to claim 18, characterized in that the power generating device is arranged in a tower head (1 1 ), the turbine (1 ) being arranged at a first end of the tower head (1 1 ) and the generator (2) being arranged at a second end of the tower head (1 1 ).

20. A wind power unit according to claim 19, characterized in that the tower head (1 1 ) is arrow-shaped, the turbine hub (15) being included in a front part of the tower head (1 1 ) shaped as an arrow point.