Patent Application
20120070296
This application claims priority of German patent application no. 10 2010 046 519.4, filed Sep. 22, 2010, the entire content of which is incorporated herein by reference.
The invention relates to a rotor blade or a rotor blade segment for a wind turbine which is fixed on a rotor hub or on a further rotor blade segment with a cable.
Conventionally, the connection of a rotor blade with a rotor hub is done by threaded fastener engagement of the rotor blade with a flange of the rotor hub. For this, the rotor blade can either also have a flange through which threaded bolts are passed, or the threaded bolts can be anchored in a wall of the rotor blade, for example, by threadably engaging in a metal cylinder having a threaded hole which is received in a bore in the wall of the rotor blade which runs perpendicularly to the longitudinal direction of the threaded connector.
Also known are rotor blades subdivided into multiple rotor blade segments. A connection between the rotor blade segments can also be achieved with threaded bolts. United States patent application publication 2010/0158694 discloses specially formed inserts which are fixedly connected to the rotor blade segments and receive the threaded bolts.
From U.S. Pat. No. 7,393,184, a different modular rotor blade constructed for wind energy turbines is known. The known rotor blade is constructed “section by section” from a plurality of rotor blade segments, whereby steel cables are guided through the entire length of the individual rotor blade segments and are fixed behind an end segment at the hub end and an end segment at the rotor blade tip end. In each rotor blade segment, special reinforcing elements, which are arranged in the interior of the rotor blade, run parallel to the steel cables.
On the basis of the above, it is an object of the invention to provide a rotor blade or a rotor blade segment for a wind turbine generator which is particularly simply constructed and can be simply and stably fixed to a rotor hub or another rotor blade segment with at least one cable. It is also an object of the invention to provide a method for fixing such a rotor blade or rotor blade segment on a rotor hub or on a further rotor blade segment.
The rotor blade or rotor blade segment of the invention includes at least one cable for the fixation of the rotor blade or rotor blade segment on a rotor hub or on a further rotor blade segment, and, a connecting surface, which in the mounted state, faces the rotor hub or further rotor blade segment and from which a free end of the at least one cable protrudes for the fixation on the rotor hub or further rotor blade segment. The at least one cable is anchored inside a connecting region of the rotor blade or rotor blade segment which extends only over a longitudinal section of the rotor blade or rotor blade segment which adjoins the connecting surface.
The at least one cable can, in particular, be made of steel but can also be made of plastic. It is constructed from a plurality of elements extending in the longitudinal direction of the cable, in particular, a plurality of strands. In comparison to the massive bolts as connecting means known in the state of the art, the cross-section of the cable can be configured substantially smaller in order to achieve the same tensile strength. A reinforcement of the connecting region is thus not necessarily required. Because of its flexibility, the cable can be guided along the contour of the rotor blade, as a result of which fact cables having a greater length can be used. These have a higher elasticity and can take up tensile stress better than the known bolts.
The connecting surface can be even or curved. It faces the rotor hub or further rotor blade segment and is placed under tension therewith in the mounted state. In particular, the connecting surface can be directly adjoining a connecting surface of the further rotor blade segment or lie against a contact surface, in particular, a flange of the rotor hub. A free end of the cable protrudes from the connecting surface so that by applying a tensile force to the free end, the rotor blade or rotor blade segment can be pulled to the rotor hub or further rotor blade segment.
In the invention, the at least one cable is anchored inside a connecting region, that is to say fixedly connected with the rotor blade or further rotor blade segment. The connecting region thereby extends only over a longitudinal section of the rotor blade or further rotor blade segment which adjoins the connecting surface, and the cable is connected to the rotor blade or rotor blade segment only in this longitudinal section. The longitudinal section extends over only a portion of the total length of the rotor blade or rotor blade section. In another longitudinal section of the rotor blade or rotor blade segment, which adjoins the connecting region, the at least one cable is not anchored. A force transmission from the at least one cable to the rotor blade or the rotor blade segment occurs exclusively in the connecting region.
In contrast to the rotor blade known from U.S. Pat. No. 7,393,184, the invention does not provide that at least one cable is completely guided through the rotor blade or rotor blade segment, which in practice is problematic because of the varying cross-section of the rotor blade over its length. For this reason, the sections of the rotor blade or rotor blade segment, which are different from the connecting region, do not have to take up any tensile stresses applied by the at least one cable and do not require any special reinforcement. The rotor blade or rotor blade segment according to the invention is thus especially simply constructed.
Moreover, because of the anchoring of the cable in the connecting region, additionally an even and secure force transmission to the rotor blade or rotor blade segment is achieved. Where applicable, the connecting region can be reinforced in its entirety or in the region of the at least one cable.
In an embodiment, a fixation segment of the at least one cable is anchored in a substance-to-substance bond and/or force-fit connection and/or form-fit connection. The fixation segment is at least five times as long as the diameter of the at least one cable in the area of the fixation segment. In particular, the fixation segment can be ten times as long as the diameter of the at least one cable in the area of the fixation segment, or longer. As a result of such a fixation of the cable in a relatively long fixation segment, an introduction of force over an especially large area into the rotor blade or rotor blade segment takes place. For example, the anchoring can be substance-to-substance bonded by adhesive bonding or casting of the at least one cable in the rotor blade or rotor blade segment or by pressing-on of a sleeve onto the at least one cable, which, in turn, is connected with the rotor blade or rotor blade segment, for example, by adhesive bonding.
In an embodiment, the anchoring is established in a pre-tensioned state of the at least one cable. This leads to a uniform force transmission to the rotor blade or rotor blade segment over the length of the anchored cable segment.
In an embodiment, an anchoring element on or in which the at least one cable is fixed is arranged within the connection region. For example, the anchoring element can be a sleeve in which the at least one cable is anchored in a force-fit and/or form-fit manner, where appropriate, in a pre-tensioned state. The anchoring element can be connected to the rotor blade or rotor blade segment in a force-fit or form-fit manner. The force is introduced into the rotor blade via the anchoring element.
In an embodiment, the at least one cable is guided through the anchoring element and fixed behind the same. For example, the anchoring element can be a metal plate with a bore through which the at least one cable is passed. The metal plate can be fixedly connected with the rotor blade or rotor blade segment, for example, by adhesive bonding or laminating in the manufacture of the rotor blade or rotor blade segment. The fixation of the at least one cable behind the anchoring element can, for example, be done with the aid of a pressed-on sleeve or a cable clamp.
In an embodiment, one end of the cable, in particular, the end guided through an anchoring element, has a cable end sleeve. The cable end sleeve can be potted with the end of the cable or pressed in with the end of the cable. The cable end sleeve can have a thread on which the cable end sleeve can be fixed, in particular, behind an anchoring element, for example, with a nut.
In an embodiment, the anchoring element is a tube or a hose which is embedded in the wall of the connecting region. The anchoring element can, at the same time, provide a guide for the at least one cable. In this case, the anchoring element can be embedded in the wall of the connecting region already during the manufacture of the rotor blade or rotor blade segment, in particular, by lamination. Subsequently, the at least one cable can be introduced into the anchoring element and be anchored therein or therebehind. Alternatively, it is also possible that the at least one cable is anchored in the anchoring element prior to the embedding of the same, in particular, in a pre-tensioned state, and that subsequently the anchoring element is embedded during the manufacture of the rotor blade or rotor blade segment. This can simplify the manufacture because the anchoring of the cable in the anchoring element can be pre-manufactured independently of further manufacturing steps of the rotor blade or rotor blade segment.
In an embodiment, the at least one cable has a curved course in the connecting region. In particular, the at least one cable runs at a uniform distance from an outer surface of the connecting region, in particular, an aerodynamic surface. In this way, the force transmission from the at least one cable into the rotor blade or rotor blade segment can be optimally adapted to the load carrying capacity of the connecting region.
In an embodiment, an end segment of the at least one cable inside the connecting region protrudes from an inner surface of the connecting region, that is the end segment points toward the interior of the rotor blade. The end segment is located at the end of the cable anchored in the connecting region. It can run at an angle to an outer surface, in particular, an aerodynamic surface of the rotor blade. The end segment can be straight or curved. The inner surface of the connecting region, from which the end segment protrudes, can be an inner side of a wall of the connecting region and be arranged essentially parallel to the outer surface of the connecting region, or at an angle thereto. The inner surface can have a step or form a step from which the end segment protrudes. The protruding end segment is easily accessible from an inner side of the rotor blade or rotor blade segment, both for assembly purposes during the anchoring and for maintenance purposes.
In an embodiment, a longitudinal segment of the at least one cable is not connected to the connecting region between the connecting surface and a segment anchored in the connecting region. The at least one cable thus runs freely in the longitudinal segment and can elastically take up changing tension. It is thus especially quite possible to set a desired pre-tensioning and to maintain it permanently.
In an embodiment, the connecting region has a length of 30 cm or more. The connecting region can also extend over a length of 50 cm, 75 cm or 1 m or more. A relatively long length of the connecting region facilitates a uniform introduction of force into the rotor blade or rotor blade segment via a large area.
The object given above is also solved by the method for fixing a rotor blade or rotor blade segment on a rotor hub or on a further rotor blade segment of a wind turbine.
At least one cable for the fixation of the rotor blade or rotor blade segment on a rotor hub or on the further rotor blade segment is provided. A connecting surface, in the mounted state, faces the rotor hub or further rotor blade segment and from this connecting surface, a free end of the at least one cable protrudes for fixation on the rotor hub or further rotor blade segment. The at least one cable is anchored inside a connecting region of the rotor blade or rotor blade segment and extends only over a longitudinal section of the rotor blade or rotor blade segment which adjoins the connecting surface.
The method according to the invention has the following steps: providing the rotor blade or rotor blade segment and providing a rotor hub or a further rotor blade segment on which the rotor blade or rotor blade segment is to be fixed; arranging the rotor blade or rotor blade segment and rotor hub or further rotor blade segment in a designated mounting position in which the connecting surface faces the rotor hub or further rotor blade segment; and, anchoring the protruding end of the at least one cable in or on the rotor hub or further rotor blade segment.
In view of the method features, reference is made to the above description of the rotor blade or rotor blade segment according to the invention. After anchoring the protruding end of the at least one cable, a heavy-duty connection of the two components is achieved. The method is especially easy to execute because one of the two ends of the at least one cable can already be anchored during the manufacture of the rotor blade or rotor blade segment. At the construction site, only the protruding end of the at least one cable must still be anchored on the rotor hub or further rotor blade segment.
In an embodiment of the method, during the anchoring of the protruding end of the at least one cable in a first step, a defined pre-tensioning is generated and subsequently a fixation of the protruding end takes place. The defined pre-tension can, for example, be generated with a hydraulic clamping tool or any other clamping tool. The fixing of the protruding end can, for example, be done by threadably engaging a nut onto an end sleeve having a thread at the protruding end of the at least one cable. After such a fixation, the clamping tool can be removed and the defined pre-tension will be maintained. In particular, in connection with a segment-like free running cable, the defined pre-tensioning can be maintained exactly and permanently.
In a further embodiment, the protruding end of the cable is anchored on the rotor hub or further rotor blade segment, as described above in relation to the anchoring of the cable segment arranged inside the connection region of the rotor blade or rotor blade segment. For example, a fixation section of the protruding end of the cable can be anchored in a substance-to-substance bond and/or force-fit connection and/or form form-fit connection over a certain length, where appropriate, in the pre-tensioned state of the cable, et cetera. In the case of a connection of two rotor blade segments, the further rotor blade segment can also have a connecting region with one of the above described characteristics. In particular, both ends of the at least one cable can be anchored in the same way in the connection of two rotor blade segments.
The invention will now be described with reference to the drawings wherein:
The rotor blade 10 shown in
The end of the wall (30, 32) shown in
The walls (30, 32) are thickened inwardly in the connecting region 24. A tube 40 made of steel has one end thereof flush with the connecting surface 38 and is embedded in the thickened region of the walls (30, 32) for each cable 26. The anchoring elements configured as tubes 40 were laminated in during the construction of the walls (30, 32) of fiber reinforced plastic material. At the ends of the tubes 40 remote from the connecting surface 38, a further anchoring element adjoins in the form of a metal plate 42 having a bore 44. The cables 26 are guided through the tubes 40 and the bore 44 in the metal plates 42. Behind the metal plates 42, each cable is secured with a pressed-on retaining element 46.
In the sectional enlargement of
The second embodiment of
In
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 046 519.4 | Sep 2010 | DE | national |
