DESC:FIELD OF THE INVENTION:

The invention relates to a wind turbine and its nacelle cover. More particularly, the present invention discloses an improved nacelle cover of a wind turbine and its mounting arrangement for connecting the nacelle cover to the main frame or main structure of the wind turbine.

BACKGROUND

Up to now, the mounting arrangement or suspension of a nacelle cover (housing cover / hub cover) on the main frame, generator frame or hub of a wind turbine has been achieved by means of rigid welded profiles or casted parts, and screw connections. These are required to be substantial and heavy as, in addition to forces, they also have to transfer torques/moments which are induced in the nacelle cover by external loads (e.g. snow and wind loads).

A disadvantage of the abovementioned form of mounting arrangement is that it needs to be mounted at every single mounting position, typically five positions on each side of the nacelle, for each individual model of a wind turbine, as well as for different types of system. This results in high expenditure and effort with respect to developing, designing/constructing, as well as producing the wind turbines.

A further disadvantage is the difficulty in adjusting the nacelle cover relative to the main frame or on the generator frame or hub. Various factors are required to be taken into account such as manufacturing tolerances for the nacelle cover, the ability to adjust the mounting arrangement along three axes and the like. Till date, this adjustability factor has been realized via elongated hole (slot) connections, in which bolts/screws can slide within slots while untightened. Thus, to perform adjustment, several screw connections per mounting point of the mounting arrangement need to be loosened, moved and tightened. This is very difficult and time consuming due to the limited space between the nacelle cover and the nacelle structure.

Furthermore, due to the heavy weight of known mounting arrangements – to cope with external loads (e.g. snow and wind loads) – it is generally impossible for one person alone to mount them.

The present invention seeks to overcome the aforementioned problems and provide an improved wind turbine, nacelle cover and mounting arrangement thereof.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide an improved wind turbine, nacelle cover and mounting arrangement thereof which is less cumbersome and easy to handle.

Another object of the present invention is to provide an improved wind turbine, nacelle cover and mounting arrangement thereof, which minimizes/eliminate the use of rigid welded profiles or casted parts and screw connections.

Yet another object of the present invention to provide an improved wind turbine, nacelle cover and mounting arrangement thereof which takes care of various factors such as snow and wind loads while mounting the nacelle cover on to the wind turbine.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a wind turbine comprising a nacelle, said nacelle being attached to a main frame suitable for carrying a number of components such as a generator, a rotor shaft, and a hub comprising rotor blades. The nacelle further comprises a nacelle cover covering the components installed on the main frame. The nacelle cover is attached to the main frame via joints having at least one degree of freedom.

Preferably, the joints have at least two degrees of freedom.

In one embodiment, the joints include one or more ball head joints. In another embodiment, the joints include one or more swivel head joints. In other embodiments, the joints include one or more cardanic joints, or include one or more fork head joints having one degree of freedom.

Preferably, the joints comprise tripod suspensions.

Preferably, the nacelle cover comprises at least two counterplates for joining two respective positions on the main frame. Preferably, for each counterplate, a tripod suspension comprises at least three rods extending therefrom. Preferably, for the or each tripod suspension, the angular spacing of rods, when viewed in a direction perpendicular to the plane of the counterplate, is 90 degrees or more.

In one embodiment, for the or each tripod suspension, first and second rods thereof are disposed in a horizontal plane. A third rod may be disposed in a vertical plane.

In another embodiment, for the or each tripod suspension, the angular spacing of rods is equal such that, when viewed in a direction perpendicular to the plane of the counterplate, the angular spacing is 120 degrees.

Preferably, two of the rods are connected to the counterplate via fixing elements defining a vertical axis of rotation, whereby, in use, each rod is rotatable about a respective axis.

Preferably, two of the rods are connected to the counterplate via swivel head joints such that, in use, each rod is rotatable about its axis of elongation by a predetermined angle x.

Preferably, two of the rods are connected to the counterplate via ball head joints such that, in use, each rod is rotatable about a horizontal axis a predetermined angle x.

Alternatively, two of the rods are connected to the counterplate via cardanic joints or by fork-head joints such that, in use, each rod is rotatable about an axis a predetermined angle x.

In each case, the predetermined angle x may lie in the range 5-20 degrees, more preferably, 10-20 degrees, more preferably, 15-20 degrees, and more preferably is 15 degrees,

In one embodiment, joints include tubular rods engageable with respective fixing elements on the nacelle cover and on the main frame, the tubular rods and fixing elements having cooperating threads, whereby the distance between the nacelle cover and the main frame can be adjusted by screwing or unscrewing a rod relative to a fixing element.

According to another aspect of the invention there is provided a nacelle cover for the above-described wind turbine.

According to another aspect of the invention there is provided a mounting arrangement for the above-described wind turbine, or for the above-described nacelle cover, the mounting arrangement being configured for attaching the nacelle cover to the main frame of the wind turbine and comprising joints having at least one degree of freedom.

In embodiments, the invention relates to a torque-free tripod-mounting which only transfers tensile forces and compression forces. In embodiments, for the transmission of horizontal and vertical loads, instead of conventional suspensions, three rods which can easily be adjusted in their length are used per each suspension point. In embodiments, these tension/compression rods are mounted torque-free at their suspension points on the nacelle and main frame by rod-end bearings. In embodiments, the adjustability of the rod length is provided by using rods with external thread in connection with rod-end bearings with internal thread.

In embodiments, the tripod suspension (tripod-mounting) comprises three rod elements per suspension point. The tripod suspension is such that external forces and reactions to those forces result in only either tensile or compressive forces within the rods of the tripod.

In embodiments, the three rod elements are in general aligned in different directions (horizontally/vertically) to transfer the induced loads from the nacelle cover to the nacelle structure.

In embodiments, the rod elements are formed of a threaded rod, two swivel head elements and two fastening elements connecting the ball heads with the nacelle structure or nacelle cover. In embodiments, the fastening elements are configured so as to allow unimpeded rotation and twisting of the swivel heads which is defined by the constructional design of the swivel heads.

In embodiments, the tripod-mounting is alternatively executed by means of a universal joint or Cardan joint arrangement. In embodiments, the Cardan joints having perpendicular rotary axes are used to realize a torque-free mounting.

With the present invention, the expenditure with respect to constructing and producing can be significantly reduced. The solution can be used cross-platform (or in different systems). At the same time, maintenance during operation of the systems can be reduced by selecting suitable system components.

In the present system, an easy adjustment is carried out over the length of the tension rods / compression rods, which, due to the smaller dimensions, can be done relatively easy and without hydraulic torque wrench.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the invention will become apparent from the drawings according to the description. In the drawings:

Figure 1 (PRIOR ART) shows a known wind turbine with nacelle,
Figure 2 (PRIOR ART) shows a cross sectional view of the nacelle (2) for the wind turbine (1) of Figure 1;
Figure 3 (PRIOR ART) shows an exploded view of a nacelle cover (4) of the nacelle (2) of Figure 2, composed of several sub-elements;
Figure 4 shows a main structure within the nacelle of a wind turbine, including the main frame (10) which is rotatably positioned on the tower (3) (Figure 1) and carries the components mentioned above, among others, according to an embodiment of the invention;
Figure 5 is an enlarged view of one of the joints (12) of Figure 4;
Figure 6 is an enlarged view of a joining element (14) according to an embodiment of the invention;
Figure 7 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with two horizontally arranged rods (20’);
Figure 8 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with rods (20’) equally angularly arranged;
Figure 9 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with joining elements (14) formed by Cardan joints (27);
Figure 10 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with joining elements (14) formed by Cardan joints (27); and
Figure 11 is an enlarged view of one of the joints (12) of Figure 4, according to another embodiment of the invention.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. Any ambiguity or confusion in relation to the functioning/working of the present invention can be understood by way of conjoint reading of detailed description in light of the drawings annexed herewith.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 (PRIOR ART) shows a known wind turbine (1) with a tower (3) and a nacelle (2) rotatably mounted on the tower (3). The nacelle (2) comprises a nacelle cover (4) mounted on a main frame (not shown), which will be discussed in further detail below. On a rotor shaft (not shown) inside the nacelle (2) a rotor (7) is arranged, which in turn comprises a hub (5) and at least one rotor blade (6).

Figure 2 (PRIOR ART) shows a cross sectional view of the nacelle (2) of the wind turbine (1) of Figure 1. In the nacelle (2) a drive train is provided which comprises a rotor shaft (8), which is rotatably mounted on a main frame (10) and connected to a generator (9) via, if necessary, a transmission.

Figure 3 (PRIOR ART) shows an exploded view of a nacelle cover (4) of the nacelle of Figure 2. The nacelle cover (4) of the nacelle (2) is composed of several parts. It should be emphasized that the described embodiment of the modular nacelle cover (4) has no limiting effect on the invention. In the case illustrated here, the nacelle cover (4) is composed of at least nacelle lower left element (4a), nacelle lower right element (4b), and a nacelle top element (4c). The mounting of the nacelle cover (4) on the main frame (10) will be discussed in detail hereinafter.

Figure 4 shows the main frame (10) which is rotatably positioned on the tower (3) (Figure 1) and carries the components mentioned above, among others, according to an embodiment of the invention. In this embodiment, a mounting arrangement (not shown) comprises, five mounting positions on each side of main frame (10) also referred as “joints” (12) having respective mounts for the purpose of mounting one lateral element (here (4c)) of the nacelle (4) (Figure 3) on the main frame (10). The said mounting arrangement can be employed for nacelle lower left element (4a), nacelle lower right element (4b), and a nacelle top element (4c) as well . It will be appreciated, however, that two to four, or six or more, mounting positions, and joints (12), per side of nacelle cover (4) may be employed in practice.

Figure 5 is an enlarged view of one of the joints (12) of Figure 4. The joint (12) comprises a counter plate (13) for attachment to and support of a respective side (lateral element) (4c) of the nacelle cover (4) of Figure 2. In this embodiment, the joint (12) forms a tripod suspension and is comprised of three joining elements (14) connecting counter plate (13) to wall (15) of mainframe (10). The joining elements (14) comprise, at each end, a fixing element (16), the latter comprising two L-brackets (17) having a spacing (18) there between in which a vertical aligned axle (19) is mounted, bolted to the wall (15) and to the counter plate (13).

Each joining element (14) comprises a rod (20) having head elements (21) attached thereto at either end. The head elements (21) have recesses (not shown) through which axle (19) passes, thereby non-rigidly connecting each fixing element (16) to the rod (20). In this embodiment, rod (20) comprises a solid rod, e.g. made of steel, and the head elements (21) are shaped so that the end of each joining element (14) operates as a swivel head joint. Thus, as well as rotation about the axis of the axle (19), the rod (20) is free to rotate about its own axis of elongation.

Figure 6 is an enlarged view of a joining element (14) according to an embodiment of the invention. This illustrates an embodiment in which the head elements (21) are shaped so that the end of each joining element (14) operates as a ball head joint. Thus, at the time of rotation about the axis (22) of the axle (19), the rod (20) is free to rotate about its own axis of elongation (23), as well as in a vertical plane due to the recess in head elements (21) being of greater internal diameter than the outer diameter of the axle (19). The joining element (14) in this embodiment has three degrees of rotation.

Except for the rotations about the axle (19) (axis (22)), which may be of considerably greater magnitude, the possible angular rotation of joining element (14) in each of the horizontal and vertical planes may be up to x degrees, where x lies in the range 5 to 30, more preferably 10 to 20, or x is 15.

In the embodiment of Figure 6, rod (20) comprises a hollow tube, e.g. made of steel, having an inner thread (not shown) that cooperates with an outer thread (not shown) on the head element(s) (21). This may be used in order to reduce the effective length of the joining element, with tightening/adjustment accomplished using nut (26).

Figure 7 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with two horizontally arranged rods (20’), i.e. Figure 7 (a) in plan view, Figure 7 (b) in lateral view and Figure 7 (c) in isometric view. As depicted in Figure 7(a) viewed from above, horizontal rods (20’) make an angle ? with the central rod (20) (oriented in a vertical plane) of c.45 degrees (Figure 7(a)). Also, as viewed from the side (Figure 7(b)), the central rod (20) is elevated from the horizontal rods (20’) by an angle a of c.45 degrees. Consequently, when viewed in a direction (arrow A in Figure 7(c)) perpendicular to the plane of the counterplate (13), the central rod (20) makes an angle of c. 90 degrees with each of the horizontal rods (20’). With this arrangement, the horizontal rods (20’) primarily are acted upon by horizontal load, and the central rod (20) takes on vertical loads.

Figure 8 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with rods (20) equally angularly arranged, i.e. Figure 8 (a) in isometric view and Figure 8 (b) in lateral view. As viewed in a direction (arrow A) perpendicular to the plane of the counter plate (13), there is an angle f of c. 120 degrees between consecutive rods (20). With this arrangement, all rods (20) are acted upon by both horizontal loads and vertical loads.

Figure 9 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with joining elements (14) formed by Cardan joints (27). This is the same as the embodiment of Figure 7, except for the use of Cardan joints (27). In this configuration, there are again two degrees of rotational freedom for the rods (20), that is about axes (22) and (28).

Figure 10 shows a joint (tripod suspension) (12) according to another embodiment of the invention – with joining elements (14) formed by Cardan joints (27). This is the same as the embodiment of Figure 8, except for the use of Cardan joints (27).

Figure 11 is an enlarged view of one of the joints (12) of Figure 4, according to another embodiment of the invention. This is the same as the embodiment of Figure 8, except for the use of Cardan joints (27). Here, instead of swivel head joints, Cardan joints (27) having perpendicular rotary axes are used to realize a torque-free mounting.
List of Reference Signs

1 wind turbine
2 nacelle
3 tower
4 nacelle cover
4a nacelle left element
4b nacelle right element
4c nacelle top element
5 hub
6 rotor blade
7 rotor
8 rotor shaft
9 generator
10 main frame
11 mounting arrangement
12 mount / joint
13 counterplate
14 joining elements
15 wall
16 fixing element
17 L-bracket
18 spacing
19 vertical aligned axle
20 rod
20’ horizontal rod
21 head element
22 vertical axis
23 axis of elongation
25 outer thread
26 nut
27 Cardan joint
28 axis

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly not limited. ,CLAIMS:1. A wind turbine (1) comprising a nacelle (2), said nacelle (2) being attached to a main frame (10) suitable for carrying a number of components such as a generator (9), a rotor shaft (8), and a hub (5) comprising rotor blades (6), whereby said nacelle (2) further comprises a nacelle cover (4) covering the components (8, 9) installed on the main frame (10), characterized in that the nacelle cover (4) is attached to main frame (10) via joints (12) having at least one degree of freedom.

2. A wind turbine (1) according to claim 1 characterized in that the joints (12) have at least two degrees of freedom.

3. A wind turbine (1) according to claim 1 characterized in that the joints (12) include one or more ball head joints, cardanic joints or fork head joints.

4. A wind turbine (1) according to claim 1 characterized in that the joints include one or more swivel head joints.

5. A wind turbine (1) according to any of claims 1 to 4 characterized in that the joints comprise tripod suspensions.

6. A wind turbine (1) according to any of the preceding claims characterized in that the nacelle cover (4) comprises at least two counter plates (13) for joining to respective positions on the main frame (10).

7. A wind turbine (1) according to claim 6, when dependent upon claim 5, characterized in that, for each counter plate (13), a tripod suspension comprises at least three rods (20) extending therefrom.

8. A wind turbine (1) according to claim 6 or 7 characterized in that, for the or each tripod suspension, the angular spacing of rods (20), when viewed in a direction perpendicular to the plane of the counterplate (13), is 90 degrees or more.

9. A wind turbine (1) according to claim 8 characterized in that, for the or each tripod suspension, first and second rods (20’) thereof are disposed in a horizontal plane.

10. A wind turbine (1) according to claim 9 characterized in that, for the or each tripod suspension, a third rod (20) thereof is disposed in a vertical plane.

11. A wind turbine (1) according to claim 7 or 8 characterized in that, for the or each tripod suspension, the angular spacing of rods (20) is equal such that, when viewed in a direction (A) perpendicular to the plane of the counterplate (13), the angular spacing is 120 degrees.

12. A wind turbine (1) according to claim 7, or any claim dependent thereon, characterized in that two of the rods (20) are connected to the counterplate (13) via fixing elements (16) defining a vertical axis of rotation (22), whereby, in use, each rod (20) is rotatable about a respective axis (22).

13. A wind turbine (1) according to any of claims 7 to 12, when dependent on claim 4, characterized in that two of the rods (20) are connected to the counterplate (13) via swivel head joints such that, in use, each rod (20) is rotatable about its axis of elongation (23) by a predetermined angle x, where x is for example in the range 5-30 degrees, and is preferably approximately +/- 15 degrees.

14. A wind turbine (1) according to any of claims 7 to 12, when dependent on claim 3, characterized in that two of the rods (20) are connected to the counterplate via ball head joints such that, in use, each rod is rotatable about a horizontal axis by a predetermined angle x, where x is for example in the range 5-30 degrees, and is preferably approximately +/- 15 degrees.

15. A wind turbine (1) according to any of the preceding claims characterized in that joints (12) include tubular rods (20) engageable with respective fixing elements (16) on the nacelle cover (4) and on the main frame (10), the tubular rods (20) and fixing elements (16) having cooperating threads (25), whereby the distance between the nacelle cover (4) and the main frame (10) can be adjusted by screwing or unscrewing a rod (20) relative to a fixing element (16).

16. Nacelle cover (4) for the wind turbine (1) according to any of the preceding claims.

17. Mounting arrangement (11) for the wind turbine (1) according to any of claims 1 to 15, or for the nacelle cover (4) of claim 16, the mounting arrangement (11) being configured for attaching the nacelle cover (4) to the main frame (10) of the wind turbine (1) and comprising joints (12) having at least one degree of freedom.