Abstract:
A wind turbine including a rotatable part, at least one absorber element secured to the rotatable part within an interior of the wind turbine, the at least one absorber element at least partly comprising lubricant absorbing material, wherein the absorber element is configured to absorb emerging lubricant inside the wind turbine is provided. Further, a rotor hub for a wind turbine, an absorber element for a wind turbine and a method for maintaining a clean environment in a wind turbine is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to EP Application No. 14170346.2, having a filing date of May 28, 2014, the entire contents of which are hereby incorporated by reference. 
       FIELD OF TECHNOLOGY 
       [0002]    The following relates to a wind turbine, a rotor hub for a wind turbine, an absorber element for a wind turbine and a method for maintaining a clean environment in a wind turbine. 
       BACKGROUND 
       [0003]    Alternative energy sources have become much more necessary as fossil fuels are depleted and pollute the environment. Wind energy is one of the most cost effective of all types of renewable energy. However, to make wind a viable source of energy or electricity in particular careful design of wind-capturing machines is necessary. A variety of principles of physics are used to create wind turbines that can efficiently capture energy from the wind. Wind turbines can be onshore or offshore. 
         [0004]    A wind turbine typically includes a tower, a nacelle supported by the tower and a rotor mounted to the nacelle. The rotor is coupled via a drive train to a generator housed inside the nacelle. The rotor includes a central rotor hub and a plurality of blades mounted to and extending radially from the rotor hub. 
         [0005]    A wind turbine typically includes many bearings that provide relative movement between adjacent parts in a relatively efficient, low-friction manner. Bearings typically require lubrication like, e.g., oil or grease to operate in with low friction and prolong their lifetime. 
         [0006]    In an exemplary situation of an oil spillage caused by, e.g., leaking blade bearings of a hydraulic blade pitch system, there is a need for absorbing hydraulic oil wasted inside the rotor hub. Thereby, it is a general intention to collect and/or absorb the oil before escaping the rotor hub and before causing environmental damage to the nearest surrounding of the wind turbine. 
         [0007]    WO2012/113402 A1 relates to a sealing system for a wind turbine comprising a first component and a second component positioned proximate the first component and movable relative thereto. An absorbent element is secured to the first component and comprises an oil-absorbent material. 
         [0008]    An alternative exemplary embodiment of oil absorbing would be the utilization of watercut oil absorbing plates, directly mounted at reinforcement plates of the blade bearings. However, the installation of such kind of absorbing plates is expensive and not satisfying with regard to service and maintenance activities. As a further disadvantage, such absorbing plates cannot be secured or mounted during initial installation or production of a wind turbine as they are hindering the installation of rotor blades during, e.g., erection of the wind turbine. 
       SUMMARY 
       [0009]    An aspect relates to an improved approach for a wind turbine to ensure effective absorbing of oil or grease. 
         [0010]    In order to overcome this problem, a wind turbine is provided, comprising
       a rotatable part;   at least one absorber element secured to the rotatable part within an interior of the wind turbine;   the at least one absorber element at least partly comprising lubricant absorbing material, wherein the absorber element is configured to absorb emerging lubricant inside the wind turbine.       
 
         [0014]    The absorber element according to the proposed solution has a low complexity and a simple design. The proposed absorber element can be secured/mounted during production of the wind turbine without hindering, e.g., the installation of rotor blades. 
         [0015]    Thus, securing one or a number of absorber elements to a rotatable part within the interior of the wind turbine is a simple and cheap solution for absorbing any lubricant wasted inside the wind turbine. The rotatable part may be able to rotate about the same or approximately about the same rotation axis as a rotor hub or a generator of the wind turbine. 
         [0016]    Due to the ongoing rotation of the rotating part of the wind turbine the lubricant like, e.g., oil spillage will run past the absorber element continuously where it will be collected and absorbed. 
         [0017]    In an embodiment, the lubricant absorbing material comprises oil-absorbent and/or grease-absorbent material. 
         [0018]    In another embodiment, the lubricant absorbing material comprises polypropylene. 
         [0019]    In a further embodiment, the at least one absorber element comprises a container with the lubricant absorbing material located inside the container. 
         [0020]    The at least one absorber element may be also a box or any other element with a shape adjusted to the respective characteristics of the interior within the wind turbine. 
         [0021]    In a next embodiment, the container comprises at least one hole and/or at least one opening. 
         [0022]    Wasted lubricant running past the container will pass through the at least one hole and/or the at least one opening and will be collected and absorbed by the lubricant absorbing material housed by the container. 
         [0023]    It is also an embodiment that the at least one absorber element is secured to the rotatable part of a rotor hub of the wind turbine. 
         [0024]    Pursuant to another embodiment, the at least one absorber element is secured
       to at least one reinforcement plate located within an interior of the rotor hub, or   to an inner surface of the rotor hub.       
 
         [0027]    According to an embodiment, at least a part of the at least one hole and/or the at least one opening of the container is located at a side of the container closest to the at least one reinforcement plate or to the inner surface of the rotor hub. This allows easy access of wasted lubricant running past the container to the absorbing material located inside the container. 
         [0028]    According to another embodiment, the absorber element comprises at least one guiding means for guiding the lubricant to the absorber element. 
         [0029]    One embodiment of the at least one guiding means may be, e.g., oil guides in form of plates or shovels, guiding or shoveling the lubricant to the absorber element. 
         [0030]    The problem stated above is also solved by a rotor hub for a wind turbine, comprising
       a rotatable part;   at least one absorber element secured to the rotatable part within an interior of the rotor hub;   the at least one absorber element at least partly comprising lubricant absorbing material, wherein the absorber element is configured to absorb emerging lubricant inside the rotor hub.       
 
         [0034]    The problem stated above is also solved by an absorber element for a wind turbine, comprising
       at least one securing element for securing the absorber element to a rotatable part within an interior of the wind turbine;   lubricant absorbing material, wherein the absorber element is configured to absorb emerging lubricant inside the wind turbine.       
 
         [0037]    In an embodiment, the absorber element comprises a container with the lubricant absorbing material located inside the container. 
         [0038]    In yet another embodiment, the container comprises at least one hole and/or at least one opening. 
         [0039]    The problem stated above is also solved by a method for maintaining a clean environment in a wind turbine, comprising the following steps:
       securing at least one a absorber element to a rotatable part of the wind turbine, the at least one absorber element comprising lubricant absorbing material;   operating the wind turbine, so that the rotatable part of the wind turbine rotates relative to a static part of the wind turbine; and   absorbing emerging lubricant inside the wind turbine with the at least one absorber element.       
 
     
    
     
       BRIEF DESCRIPTION 
         [0043]    Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
           [0044]      FIG. 1  shows an exemplary schematic overview of a wind turbine; 
           [0045]      FIG. 2  illustrates a schematical view of an interior of a rotor hub thereby showing an exemplary embodiment of the proposed solution; 
           [0046]      FIG. 3  illustrates a more detailed schematical view of an embodiment of the absorber element as shown in  FIG. 2 ; and 
           [0047]      FIG. 4  illustrates in an exemplary schematical view of an alternative embodiment of the proposed solution. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    With reference to  FIG. 1  an exemplary schematic overview of a wind turbine  100  is shown. The wind turbine  100  comprises a tower  110 , a nacelle  120  and a rotor hub  140 . The nacelle  120  is located on top of the tower  110 . The rotor hub  140  comprises a number of wind turbine blades  150 . The blades  150  may be rotatable mounted to the rotor hub  140  by respective blade bearings  155  allowing the blades  150  to be pitched into or out of the wind. 
         [0049]    The rotor hub  140  is mounted to the nacelle  120  such, that it is able to rotate about a rotation axis  105 . A generator  125  is located inside the nacelle  120 . The wind turbine  100  can be, e.g., a direct drive wind turbine. 
         [0050]      FIG. 2  illustrates a schematical view of an interior  200  of a rotor hub thereby showing an exemplary embodiment of the proposed solution. The interior  200  of the rotor hub represents a rotatable part of a wind turbine. 
         [0051]    A hydraulic blade pitch system  210  is located in the interior  200  of the rotor hub, being attached via a first support element  211  to a blade bearing reinforcement plate  240  and via a second support element  212  to a, e.g., casted inner surface of the rotor hub. 
         [0052]    According to the exemplary scenario as shown in  FIG. 2 , oil is leaking of the hydraulic blade pitch system  210  causing oil spillage  260  within the interior  200  of the rotor hub like, e.g., on a surface of the blade bearing reinforcement plate  240 . 
         [0053]    To enable absorption of the oil spillage  260 , two absorber elements  220  comprising lubricant absorbing material are secured to the blade bearing reinforcement plate  240  via securing elements  250 . Any shape may be possible for the absorber elements  220 , preferable adjusted to the characteristics (like, e.g., available space) of the interior  200  of the rotor hub. According to the example as shown in  FIG. 2 , each absorber element  200  comprises a box or container housing the lubricant absorbing material inside. 
         [0054]    It should be noted, that an arbitrary number of absorber elements or boxes  220  can be placed within the interior  200  of the rotor hub, dependent on, e.g., the characteristics of the interior  200  of the rotor hub. 
         [0055]    As an example, one or several oil absorbing pillows can be used as lubricant absorbing material placed inside each of the boxes  220 . Alternatively, oil absorbing cloth or oil absorbing pulp may be used. 
         [0056]    The boxes  220  may be made of any material like, e.g., metal or composite, being qualified to withstand hydraulic oil. 
         [0057]    According to a further embodiment of the proposed solution, the absorber element may at least partly or purely consist of the lubricant absorbing material which may have, e.g., the shape of a box or container. 
         [0058]    It should be further noted, that the lubricant absorbing material may be directly secured within the interior  200  of the rotor hub like, e.g., secured directly to the blade bearing reinforcement plate  240  or to the inner surface of the rotor hub. 
         [0059]    The lubricant absorbing material may be any material enabling absorption of hydraulic oil like, e.g., polypropylene. 
         [0060]    As shown in  FIG. 2 , the boxes  220  are attached to the blade bearing reinforcement plate  240  and therefore being part of a rotatable part of the rotor hub. Hence, during operation of the wind turbine and due to the ongoing rotation of the rotor hub, the oil spillage  260  will run past the boxes  220 . 
         [0061]    According to a preferred embodiment, each of the boxes  220  comprises several holes or openings  230  to enable proper access of the oil spillage  260  to the lubricant absorbing material placed inside the boxes  220 . Preferably, at least a part of the holes or openings (not visible) are located at a side of the box closest to the reinforcement plate  240  allowing easy access of the oil spillage  260  to the lubricant absorbing material. 
         [0062]    According to an advanced embodiment of the proposed solution (not shown), additional oil guides in form of plates or shovels are placed within the interior  200  of the rotor hub, e.g., being attached to the blade bearing reinforcement plate  240 . By the use of theses plates or shovels and due to the ongoing rotation of the rotor hub, the oil spillage  260  will be guided or shoveled to the boxes  220 . 
         [0063]      FIG. 3  illustrates a more detailed schematical view of the absorber elements shown in  FIG. 2 . An absorber element  300  comprising a box is secured to a surface of a blade bearing reinforcement plate  310  via securing elements  320  like, e.g., screws. The box  300  comprises several holes or openings  330 . 
         [0064]    By using one or several distance elements  340 , a gap (illustrated by a double arrow  345  in  FIG. 3 ) is provided between the box  300 , i.e. a side of the box  300  being closest to the blade bearing reinforcement plate  310  and the surface of the reinforcement plate  310 . Further, a side of the box  300  being closest to the reinforcement plate  310  provides several holes or openings (not visible). According to an alternative embodiment, the box  300  is at least partly open towards the surface of the reinforcement plate  310 . 
         [0065]    Due to the ongoing rotation of the rotor hub, wasted oil spillage  350  can move or pass through the gap  345  and the holes or openings  330  into the interior of the box  300  and thus will be absorbed by lubricant absorbing material (not visible in  FIG. 3 ) located inside the box  300 . 
         [0066]      FIG. 4  illustrates in an exemplary schematical view an alternative embodiment of the proposed solution located within an interior  400  of a rotor hub. The interior  400  is part of or representing a rotating part of the rotor hub. 
         [0067]    Contrary to the exemplary embodiment as shown in  FIG. 3 , an absorber element  430  comprising or housing lubricant absorbing material (not visible) is secured to the casted inner surface  450  of the rotor hub. According to the exemplary embodiment as shown in  FIG. 4 , the shape of the absorber element  430  is adapted to the interior  400 , i.e. the inner surface  450  of the rotor hub like, e.g., fitting between two support elements  410  used for, e.g., mounting components of a hydraulic blade pitch system (not shown) within the interior  400  of the rotor hub. 
         [0068]    The absorber element  430  comprises several holes or openings  440  enabling access of oil spillage to the lubricant absorbing material located inside the absorber element  430 . Due to ongoing rotation of the rotor hub during operation of the wind turbine, occurring oil spillage will be guided through the holes or openings  440  of the absorber element  430  to the lubricant absorbing material placed inside. 
         [0069]    In addition to that, due to the particular shape, the absorber element  430  may be advantageously used as a service platform, allowing comfortable service and maintenance activities within the rotor hub or wind turbine. 
         [0070]    It should be noted, that an arbitrary number of absorber elements may be placed within the interior  400  of the rotor hub, dependent on the size, available space and characteristics of the interior  400 . 
         [0071]    As an advantage, the absorber element according to the proposed solution has a low complexity and a simple design. The proposed absorber element can be secured/mounted during production of the rotor hub or the wind turbine without hindering the installation of the rotor blades. 
         [0072]    Thus, securing one or several absorber elements to the rotating part within the rotor hub or to any rotating part within the wind turbine is a simple and cheap solution for absorbing any lubricant wasted inside the rotor hub or wind turbine. Placing the absorber element within the interior of the rotor hub (like, e.g., at the blade bearing reinforcement plate) or within the interior of the wind turbine and due to the ongoing rotation of the rotor hub (or any other rotating part of the wind turbine), the lubricant like, e.g., oil spillage will run past the absorber element continuously where it will be collected and absorbed. 
         [0073]    Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. 
         [0074]    For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.