FIELD OF THE INVENTION:

The invention relates to a frame structure for a wind turbine, to a wind turbine and to a method for manufacturing a frame structure thereof.

BACKGROUND

Frame structures of wind turbines, in particular of wind turbines having a rotor with a substantially horizontal rotor axis, commonly comprise a part that carries a rotor of the wind turbine and a part that carries a generator that is driven by the rotor. Conventionally, the frame structure is made of one or more cast metal parts.

Cast metal, in particular cast iron, provides for sufficient strength and may be formed with complex shapes. However, some areas of the frame structure only have to withstand small loads compared to other areas of the frame structure, but their wall thickness cannot be reduced any further due to limitations of the casting process. Therefore, some parts of the frame structure may have a higher strength and thus weight than actually necessary.

Furthermore, it may be desirable to use different materials for different parts of the frame structure to be able to more precisely adapt the configuration of the frame structure to the specific needs in different types and sizes of wind turbines.

OBJECT OF THE INVENTION

An object of the present invention is to provide a frame structure allowing for an increased flexibility in its design, e.g. in the choice of material.

SUMMARY OF THE INVENTION

Accordingly, the frame structure comprises a main frame for supporting a rotor of the wind turbine, a generator frame for supporting a generator of the wind turbine, the generator frame comprising at least one beam, and at least one connector device (in particular two connector devices) being mounted to the main frame, e.g. by means of at least one fastening means (such as a screw, bolt or rivet). Therein, the at least one beam is mounted on the at least one connector device, e.g. by means of at least one fastening means (such as a screw, bolt or rivet), wherein the at least one connector device is arranged between the at least one beam and the main frame, for example such that the beam and the main frame are not in direct contact to one another. The generator may be driven by the rotor, the rotor by the wind. The at least one beam is adapted for carrying at least part of the weight of the generator. The beam may be mounted to the main frame such that a flux of forces due to weight forces of a mounted generator is introduced into the main frame (in particular at least predominantly) via the beam and the connector device. The connector device serves as an interface and/or adapter between the main frame and the generator frame. The generator frame (in particular the beam or the beams) may be in surface contact with the connector device. The connector device may be in surface contact with the main frame. The main frame may be formed in one piece. The connector device, the beam or beams and the main frame are separate parts, i.e. not formed in one piece.

As a result, the connector device may be formed particularly strong, e.g. by using strong materials such as iron or steel and/or a first, high wall thickness. Therefore, the connector device may be strong enough to withstand occurring forces, even if the main frame only provides a limited contact surface area. The beam or beams may be formed by the same or another type of material and/or with a wall thickness that may be varied for different wind turbines while using the same type of connector device. For example, the beam or beams may have a second, lower wall thickness. Thus, the flexibility in the design of the frame structure, in particular in the choice of materials is increased. It is, thus, possible to decrease the weight of the frame structure and/or the production costs. It may also be easier to adapt the frame structure to different types and sizes of wind turbines. The beam or beams may be formed by different materials than the connector device and/or the main frame.

According to an embodiment, the connector device (or at least one connector device) is a cast part. For example, the connector device is a cast iron part, a cast aluminum part or a cast steel part. This configuration may be advantageous when the connector device shall have a complex shape.

Alternatively or additionally, the connector device (or at least one connector device) may comprise a weld seam. The connector device may be a welded part, in particular a welded iron part, a welded aluminum part or a welded steel part. According to an embodiment, the connector device is a bent part. The connector device may comprise a bent portion. It is possible to select the material or materials used for the connector device according to the needs of a specific type and/or size of a wind turbine optimized for the needs at the interface between the main frame and the generator frame. Therefore, the flexibility in the choice of materials is increased.

The generator frame may comprise two beams. Via the two beams a support portion adapted for carrying the generator may be mounted to the main frame. The beams may be aligned substantially parallel to one another. The use of two beams can provide good strength and stiffness while maintaining a low weight of the frame structure.

According to an embodiment, the at least one beam (or each of the beams) is a bent part, in particular a bent steel part. Optionally some or all parts of the generator frame are bent parts, in particular bent steel parts. In the said embodiment at least one beam may alternatively or additionally be or comprise a welded part. In particular, the beam may be made of iron or steel. Bent steel may be made of a flat steel panel in a less complex and cost intensive process compared to casting. Bent and/or welded steel may be provided with a strength that is strong enough for the needs of the beam but not strong enough for providing an interface to the main frame. Therefore, a bent and/or welded steel beam may be connected with the main frame by means of the connector device. The connector device may have a stronger configuration, e.g. be made of cast or (thicker) welded material.

The at least one beam may comprise or may be made of steel, in particular S235 steel or S355 steel. These materials may be particularly suitable for the beam or beams. Also some or all other parts of the generator frame may comprise or be made of S235 steel or S355 steel, e.g. one or more crossbeams and/or a platform.

The frame structure may further comprise an eyelet. The eyelet may be adapted for being connected with a hoist device, in particular to serve as an anchor point for the hoist device and/or for a device for lifting a nacelle cover.

The eyelet may be provided and/or formed on the connector device. The eyelet may be arranged on a side face of the connector device. The connector device has an upper face (which is upside in use of the frame structure) and a lower face (which is downside in use), in particular connected with each other via the side face. Alternatively, the eyelet is arranged on the upper face of the connector device. Arranging the eyelet on the side face of the connector device may be advantageous, because forces acting on the eyelet on the side face can reduce torsion of the connector device with respect to an arrangement on the upper face. For example, the eyelet is formed in one piece with the connector device and/or protrudes from the side face thereof. The frame structure may further comprise a platform defining a plane. The eyelet may be arranged outside of said plane, in particular below said plane (when the frame structure is in use as intended). The plane may be substantially horizontal in use. Personnel may stand and/or walk on the platform. By arranging the eyelet below the plane of the platform, the eyelet may be no tripping hazard for personnel.

The frame structure can further comprise a positioning device for correctly positioning one part of the frame structure to another, in particular the connector device to the main frame. The positioning device may comprise a form-locking engagement means. For example, the main frame comprises a recess and the connector device comprises a positioner (and/or vice versa), the positioner may comprise a protrusion, such as a protruding edge. The recess and the positioner may have a mating configuration. By means of the positioning device mounting of the frame structure may be particularly easy and/or precise. The connector device may comprise a plurality of fastening points, in particular a plurality of holes, for example rivet holes or screw holes. The plurality of fastening points may be arranged in at least one row of fastening points, in particular at least two rows of fastening points, in particular in an array (a matrix) of fastening points. The main frame and/or the beam or beams may comprise a plurality of fastening points in an arrangement (in particular in a corresponding pattern) corresponding to the arrangement of the fastening points of the connector device. The connector device and the main frame and/or the connector device and the generator frame (in particular the beam) may be fixed to one another by means of the plurality of fastening points, e.g. using a plurality (in particular a large number) of fastening means, such as screws, bolts or rivets. A large number of comparably small fastening means may serve for a more reliable connection compared to a smaller number of comparably larger fastening means.

The object is also solved by a wind turbine comprising a frame structure according to any aspect or embodiment described herein.

The object is also solved by a method for manufacturing a frame structure for a wind turbine, in particular a frame structure according to any aspect or embodiment described herein, the method comprising the steps of: providing a main frame adapted for supporting a rotor of the wind turbine,

providing a generator frame adapted for supporting a generator of the wind turbine, the generator frame comprising at least one beam,

mounting a connector device to the main frame, and mounting the at least one beam to the at least one connector device, the at least one connector device being arranged between the at least one beam and the main frame.

The method may be performed in the order as given above, or, alternatively, in another order. For example, the connector device may be mounted first to the beam and afterwards to the main frame such as to be arranged between the beam and the main frame.

The method may comprise the step of casting iron or steel to form at least one connector device. The method may comprise the step of welding iron or steel to form at least one connector device.

The method may be adapted to manufacture a frame structure according to any aspect or embodiment described herein.

Regarding advantages of the method, reference is made to the description of the frame structure above.

By the above-described frame structure and method, a frame structure may be provided, which facilitates selection of material used for the connector device according to the needs of a specific type and/or size of a wind turbine optimized for the needs at the interface between the main frame and the generator frame.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention are shown in the figures, where

Figure 1 shows a schematic view of a wind turbine with a tower, a nacelle and a rotor;

Figure 2 shows a schematic side view of various components located within the nacelle of the wind turbine according to Figure 1 , including a frame structure and a generator; Figures 3A and show schematic views of an embodiment of a frame

3B structure having a main frame and a generator frame;

Figures 4A and show enlarged schematic views of parts of the frame

4B structure according to Figures 3A and 3B;

Figures 5A and show schematic views of two embodiments of a

5B connector device of the frame structure; and

Figure 6 shows a method for manufacturing a frame structure for a wind turbine.

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.

DESCRIPTION OF THE INVENTION

Figure 1 shows a wind turbine (2) for generating electrical energy by rotation of a rotor (22) by means of wind. The rotor (22) is mounted at a nacelle (21) arranged at an upper end (200) of a tower (20) of the wind turbine (2). The tower (20) extends between its upper end (200) and a foundation (201 ) at the ground. The tower (20) is elongate and has a longitudinal axis. The rotor (22) comprises several, in the present case three blades (221 ) mounted on a hub (220). The rotor (22) is rotatable around a rotor axis x with respect to the nacelle (21 ). The rotor blades (221) can be revolved within a rotor plane. In use, the rotor axis x is oriented substantially horizontally.

For an efficient extraction of wind energy, the rotor (22) is oriented towards the wind. In particular, the rotor plane is oriented perpendicular to the direction of the incoming wind. For this purpose, the nacelle (21) together with the rotor (22) is rotatable around a yaw axis z with respect to the tower (20). The yaw axis z corresponds to the longitudinal axis of the tower (20). The yaw axis z is substantially perpendicular to the rotor axis x. For effecting a rotation of the nacelle (21) around the yaw axis z, the wind turbine comprises a yaw system (25) (not visible in Figure 1 but shown in Figure 2).

Figure 2 shows the hub (220) of the rotor (22) according to Figure 1 , being operatively connected to a generator (24), in the present example via a main shaft and a gearbox (23). When the wind rotates the rotor (22), the hub (220) drives the generator (24), which converts the mechanical energy into electrical energy.

The rotor (22) and the generator (24) (and other parts of the wind turbine (2), e.g. the gearbox (23)) are supported on a frame structure (1). The frame structure (1) is adapted to be mounted on the tower (20) of the wind turbine (2) (according to Figure 1 at its upper end (200)), in the present example by means of the yaw system (25).

For supporting the rotor (22), the frame structure (1 ) comprises a main frame (10). The main frame (10) comprises a rotor bearing (104). By means of the rotor bearing (104) the main frame (10) supports the rotor (22). In the present example, the main shaft operatively connecting the hub (220) with the generator (24) is rotatably mounted on the rotor bearing (104). In the embodiment according to Figure 2, also the gearbox (23) is mounted on the main frame (10) (or central support portion) of the frame structure (1 ).

For supporting the generator (24) (and optionally other parts of the wind turbine (2), e.g. a nacelle cover and/or a lifting or hoist device), the frame structure (1 ) comprises a generator frame (11 ). The generator frame (11 ) has a support portion (111 ) for carrying and supporting the generator (24). In the example according to Figure 2, the support portion (111 ) comprises a platform (112) and one or more crossbeams (115) for supporting the platform (112). If the platform (112) is strong enough, the crossbeams (115) may be omitted. The generator (24) is mounted on the generator frame (11 ), in the present example by arranging and fixing it on the platform (112) (or in general on the support portion (111 )).

The generator frame (11) further comprises at least two beams (110) (in the present example exactly two beams (110)). Each beam (110) has a longitudinal extension. One longitudinal end of each beam (110) is oriented towards the main frame (10). The beams (110) are oriented substantially parallel to one another. The support portion (111 ) is mounted on the beams (110). The crossbeams (115) connect the beams (110) with one another. The platform (112) extends from one beam (110) to the other beam (110). In use at a wind turbine (2), the platform (112) is oriented substantially horizontal. Personnel may walk and/or stand on the platform (112).

Each of the beams (110) is (structurally) connected with the main frame (10) through a connector device (12). As the frame structure (1 ) according to Figure 2 has two beams (110), it also comprises two connector devices (12). The beams (110) according to Figure 2 are cast iron parts. The beams (110) have a cross-section corresponding to an H (H-beams or l-Beams). Due to the provision of the connector devices (12) acting as an adapter between the main frame (10) and the respective beam (110), the same main frame (10) may be used with different types of beams (110), thus increasing the flexibility in the design of the frame structure.

Turning now to Figures 3A and 3B, another embodiment of a frame structure (1 ) is shown. The main frame (10) according to Figures 3A and 3B differs only in minor details from the main frame (10) according to Figure 2 so that reference is made to the above description. The frame structure (1 ) according to Figures 3A and 3B differs from the frame structure (1 ) according to Figure 2 in that the beams (110') (one of two beams (110') is shown in Figures 3A and 3B) are no cast iron parts. In contrast, the beams (110') are bent parts. For manufacturing such a beam (110'), a flat component, in the present example a panel of metal, in particular of iron or steel is bent. According to Figures 3A and 3B, the beams (110') have a cross-section corresponding to a C or U (with three flat sections).

The beams (110') are tapered, e.g. for decreasing the weight and/or necessary construction space. In particular, the beams (110') are tapered towards their ends facing away from the main frame (10). The highest strength is needed in the vicinity of the connector device (12). A cross-sectional area of each of the beams (110') is larger adjacent to its end facing towards the main frame (10) than on its opposite end.

Each beam (110') is mounted on one of the connector devices (12). Each beam (110') comprises a plurality of fastening points (114) for fixing (in particular releasably fixing) the beam (110') to the connector device (12). The connector device (12) comprises a plurality of fastening points (121) (as shown in particular in Figures 4A and 4B) corresponding to the plurality of fastening points (114) of the respective beam (110'). At least some of the plurality of fastening points (114) of the beam (110') is arranged in the substantially same pattern (for example matrix pattern) as the fastening points (121) of the connector device (12). Corresponding fastening points (114, 121) of the beam (110') and the connector device (12) are connected (in particular mounted) to one another by means of a fastening means, e.g. a screw (not shown in the figures). In the present embodiment the fastening points (121 , 114) are holes. The connector device (12) and the beam (110') have corresponding fastening points (121 , 114) arranged in a plurality of different planes, in the present example in three planes (corresponding to the upper face, the side face and the lower face of the connector device (12)). Two (or in general at least two) of the planes extend substantially parallel to one another. At least two of the planes may extend substantially vertical to one another; in the present example the planes corresponding to the upper and lower faces extend substantially vertical to the plane corresponding to the side face.

The pluralities of fastening points (121 ), (114) are arranged in a plurality of rows, in particular parallel rows. The beam (110') encompasses the connector device (12) (at least) partially. The beam (110') and the connector device (12) are in surface contact with one another, in the present example the surface contact extends over said plurality of (three) planes.

Each beam (110') is spaced apart from the main frame (10). The connector device (12) is arranged between the respective beam (110') and the main frame (10). The connector device (12) is not in contact with the main frame (10). In an alternative embodiment the beam (110') and the main frame (10) are in contact with one another but the flux of forces from each beam (110') to the main frame (10) due to a weight force of the generator (24) substantially goes through the connector device (12). As shown in particular in Figures 3A and 3B, the main frame (10) comprises an interface (100) for each connector device (12). The interface (100) is connected with a mating interface (120) of the connector device (12) (see Figure 5A). In the present example, the interface (100) is a (in particular rectangular) flat surface that is in surface contact with the corresponding interface (120) of the connector device being a mating flat surface. The interface (100) of the main frame (10) comprises a plurality of fastening points (101 ). The interface (120) of the connector device (12) comprises a plurality of fastening points (123). The plurality of fastening points (101 ) at the main frame (10) is arranged in a corresponding pattern, in the present example in a plurality of rows (in particular parallel rows, in particular two rows, e.g. in a matrix pattern). The fastening points (101 , 123) presently are holes, in particular screw holes. The fastening points (123) at the interface (120) of the connector device (12) (for connecting it to the main frame (10)) are spaced apart from the fastening points (121 ) of the connector device (12) for connecting the connector device (12) with the beam (110').

A plate-like area forming the interface (100) of the connector device (12) is oriented substantially vertical to plate-like areas forming said plurality of planes of the connector device (12). Optionally and as shown in Figure 5A, the plate-like areas forming said plurality of planes of the connector device (12) are inclined towards one another (slightly deviating from an exactly vertical orientation, e.g. by below 5 degrees) to improve a support of a tapered beam (110').

As seen best in Figures 3A to 5A, the frame structure (1 ) comprises a positioning device. The positioning device comprises a recess (103) in the main frame, in particular arranged adjacent to the interface (100) of the main frame (10), namely at an (upper) edge thereof. The connector device (12) comprises a corresponding positioner (126) in the form of a protrusion. The positioner (126) and the recess (103) have a mating configuration to form a form-locking connection. The positioning device simplifies the assembly of the frame structure (1 ).

As shown in particular in Figures 3A to 5A, the connector device (12) comprises an eyelet (125). The eyelet (125) is adapted to support a hoist device of the wind turbine (2) and/or the nacelle cover. The eyelet (125) is formed (in particular as a through hole) on a tab (124) protruding from the connector device (12), in particular at a side surface thereof. The tab (124) is arranged below the upper surface of the platform (112). Due to this arrangement, the tab (124) does not form a tripping hazard for personnel. The tab (124) extends substantially in the same plane as the interface (120) of the connector device (12).

Figure 5B shows another embodiment of a connector device (12'). The connector device (12') has a similar configuration as the connector device according to Figures 3A-5A and in the following only the differences will be explained.

The connector device (12') according to Figure 5B is a welded part, in particular made of steel plates. The steel plates are welded to one another along weld seams. In the present example, the connector device (12') is made by welding a first plate (forming the interface (120) and optionally the tab (124) and eyelet (125)) to each of a plurality (in particular three) of second plates (each comprising some of the fastening points (121 ) for fastening the corresponding beam (110, 110')). The second plates are oriented substantially vertical to the first plate. Manufacturing the welded connector device (12') may be particularly simple.

With reference to Figure 6, a method for manufacturing the frame structure (1 ) according to any of the above-described embodiments will be described. At step 300, a main frame (10) that is adapted for supporting a rotor (22) of the wind turbine (2) is provided. For supporting the rotor (22), the main frame (10) comprises a rotor bearing (104).

At step 301 , a generator frame (11 ) that is adapted for supporting a generator (24) of the wind turbine (2) is provided. The generator frame (11 ) comprises a support portion (111 ) for the generator (24). The generator frame (11 ) comprises at least one beam (110, 110')

In an optional step 302A, a metal, in particular iron or steel is casted to form at least one connector device (12).

In an optional step 302B, a metal, in particular iron or steel, in particular in the form of a plurality of plates, is welded (in particular along at least one weld seam) to form at least one connector device (12').

At step 303, at least one connector device (12, 12') (e.g. from the optional steps 302A and/or 302B) is provided and mounted to the main frame (10). Mounting may be performed e.g. by use of a plurality of fastening elements such as screws. At step 304, the at least one beam (110, 110') is mounted to the at least one connector device (12, 12'). Mounting may be performed e.g. by use of a plurality of fastening elements such as screws. Steps 303 and 304 are performed such that the at least one connector device (12, 12') is arranged between the at least one beam (110, 110') and the main frame (10).

Providing the described frame structure (1 ) allows to use different types of materials for the connector device (12, 12') and for the beams (110, 110'). Furthermore it allows to use the same type of beams (110, 110') for different types of main frames (10) (e.g. having different types of interfaces) and vice versa by only adapting the interfaces of the connector devices (12, 12') to the interfaces of the main frame (1 ). This leads to an increased flexibility in the design of the frame structure (1 ), in particular in the choice of material or materials used for manufacturing the frame structure (1 ). The connector device (12, 12') serves as an adaptor. Differently configured main frames (10), beams (110, 110') and connector devices (12, 12') together form a set or construction kit for assembling one or more of a plurality of different frame structures, e.g. being adapted for different needs in different wind turbines. List of Reference Numbers

1 frame structure

10 main frame

100 interface

101 fastening point

103 recess

104 rotor bearing

1 1 generator frame

1 10, 1 10' beam

1 1 1 support portion

1 12 platform

1 14 fastening point

1 15 crossbeam

12, 12' connector device

120 interface

121 fastening point

123 fastening point

124 tab

125 eyelet

126 positioner

2 wind turbine

20 tower 200 upper end

201 foundation

21 nacelle

22 rotor

220 hub

221 blade

23 gearbox

24 generator

25 yaw system

x rotor axis

z yaw 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.