Patent Publication Number: US-2011067792-A1

Title: Adjustable Tarpaulin for Tower Sections of a Wind Turbine

Description:
FIELD OF INVENTION 
     The present invention relates to a tarpaulin device for a tower section of a wind turbine. Moreover, the present invention relates to a method of fixing a tarpaulin device to a tower section of a wind turbine. 
     ART BACKGROUND 
     During transportation of tower sections for wind turbines, the tower sections are generally covered at both ends with a tarpaulin to protect the inside of the tower sections from getting dirty and wet and to prevent corrosion. The tarpaulins are attached to each tower section. When the tower sections are attached to the transportation brackets the tarpaulins have to be fitted to the transportation bracket by cutting holes in the area of the transportation brackets to ensure an accessibility of the tower sections to the transportation brackets. The size of the holes to be cut into the tarpaulin differs depending on the used transportation bracket adapted for respective transportation means, such as ships, rail vehicles or trucks. Furthermore, the sizes of the cuts in the tarpaulin have to fit to the lifting equipment for lifting the brackets from one location to the other. 
     SUMMARY OF THE INVENTION 
     It may be an object of the invention to provide a proper tarpaulin device for a tower section of a wind turbine. 
     This object may be solved by a tarpaulin device for a tower section of a wind turbine and by a method of fixing a tarpaulin device to a tower section of a wind turbine according to the subject-matter of the independent claims. 
     According to a first exemplary embodiment of the present invention, a tarpaulin device for a tower section of a wind turbine is provided. The tarpaulin device comprises an adjustable opening, wherein a location and/or a size of the adjustable opening in the tarpaulin device are adaptable to a functional element of the tower section. 
     According to an exemplary embodiment of the present invention a method of fixing a tarpaulin device to a tower section of a wind turbine is provided. A location and a size of an adjustable opening in the tarpaulin device is adapted to a functional element of the tower section. 
     The term “functional element” may denote an additional element connected to the tower section, such as a mounting bracket or a lifting mechanic. The functional elements may be connected removably to the tower section or may be a part of the tower section itself. Furthermore, the functional elements extend from the inside of the tarpaulin device, such as from the surface of the tower section or the inside of the tower section, to the outside of the tarpaulin device for getting in functional contact with other transportation mechanics, such as transportation trains or fixing elements of transportation means. 
     The term “tarpaulin device” may denote a protecting foil or other flexible materials that cover an open end of a tower section and is for instance fixed to an edge or a margin of the tower section. 
     The term “adjustable opening” may denote an opening of the tarpaulin device through which the functional element may extend. 
     In conventional tarpaulins cut holes are cut in the tarpaulin device by a sharp element, wherein the cut holes may be uneven and in an indefinable length. Furthermore, the cut holes are oftentimes made bigger than necessary. Moreover, when cutting the tarpaulins, the tarpaulins can therefore not be used again for other transportation devices or for other tower sections. Furthermore, the cut holes may be torn bigger by wind during transportation. The larger the holes are cut during transportation the more dirt enters into the tower sections and cleaning of the tower sections is required before the tower sections are ready to be used on the site. 
     By using the tarpaulin device with its adjustable openings, that are necessary for providing an access to the functional element, may be adjusted more precisely with respect to a variety of different sized functional elements. Thus, a reduced space between the adjustable openings and the functional elements is provided, so that dirt may be prevented from entering. Furthermore, when the adjustable openings seal the inside of the tower section, no wind force due to air stream enters the openings, because the air stream will be guided around the tower section. Thus, no flattering of the tarpaulin device due to air stream occurs and a risk of damage of the tarpaulin device will be reduced. Moreover, when providing an adjustable opening, the edges of the adjustable openings may be selectively reinforced in comparison to an undefined cut in the tarpaulin device. Thus, a more precise and maintainable adjustable opening may be provided. 
     According to a further exemplary embodiment, the adjustable opening is provided by a rib section in the tarpaulin device. The length of the rib section is therefore adjustable. By providing a rib section, the size respectively the maximum length of the rib may be predefined. In contrary to cutting a cut into the tarpaulin device, the cut length would increase when a stress, such as stress by wind force, would be exerted to the tarpaulin device. When using a predefined rib section, the ends of the rib sections may be selectively reinforced, so that an unintended increase of the rib section due to stress may be prevented and a more stable tarpaulin device may be provided. 
     According to a further exemplary embodiment, the tarpaulin device further comprises a flap element for opening and closing the adjustable openings. By using the flap element, then adjustable opening may be opened when needed. When an adjustable opening is not needed, the adjustable opening may be closed by the flap element. Thus, the tarpaulin device may comprise a plurality of adjustable openings for a variety of different shaped functional elements, wherein only the active adjustable openings, namely these openings through which a functional element is extending, are adjustably opened by the flap element. Thus, the tarpaulin device may be adapted for a plurality of different shaped tower sections and/or functional elements without providing an unintended opening through which dirt may enter to the inside of a tower section. Thus, flexibility is provided without increasing the risk of an entering of dirt. 
     According to a further exemplary embodiment, the flap element comprises a sub flap element. The sub flap element is connectable to the flap element or the tarpaulin device flexibly. With an additional division of the flap element in further sub flap elements, a desired pattern of a variety of differently shaped adjustable openings may be provided. The strip line of each sub flap element may extend in different directions and thus create an individual pattern of differently shaped sub flap elements. Because each sub flap element is removable individually, the shape of the adjustable opening covered by the flap elements or the sub flap elements may individually adapted to the functional elements. Thus, a higher flexibility of the adjustable openings may be provided. 
     According to a further exemplary embodiment, the flap element is removably fixed to the tarpaulin device. The flap element may be connected with one contact side to the tarpaulin device, so that the flap element may be folded when a covered adjustable opening is needed. The folded flap element is in general not fixed, so that by wind forces the flap element is flittering around and may be damaged or may damage the functional element or the tower section. Thus, when removing the flap element, a flittering of the flap element may be prevented and a damage of the flap element may be reduced. Thus, the flap element is fixed to the tarpaulin device removably, i.e. all connecting flanges of the flap element are removably fixable to the tarpaulin device and do not comprise any irremovable connections. 
     According to a further exemplary embodiment, the tarpaulin device comprises furthermore a Velcro element for adjustably opening and closing the adjustable opening. By using Velcro elements a flexible opening of the adjustable openings may be provided. The Velcro elements may be used for adjustably opening and closing the rib sections or for opening and closing the flap elements. Furthermore, by using the Velcro element, a very quick adjustment of the adjustable openings to the different sizes of the functional elements may be provided, so that the tarpaulin device and the functional elements may be installed easily. 
     According to a further exemplary embodiment, the tarpaulin device further comprises a zip fastener element for adjustably opening and closing the adjustable opening. Furthermore, according to a further exemplary embodiment, the tarpaulin device further comprises a button stay element for adjustably opening and closing the adjustable opening. By opening a zip fastener element or a button stay element, a more rigid but flexible connection of the rib sections or of the flap elements may be provided, so that when stress is exerted to the tarpaulin device, an unintentional opening of the adjustable openings may be prevented. 
     According to a further exemplary embodiment, the tarpaulin device furthermore comprises reinforced sections located at least partially around the adjustable opening. A reinforced section may be provided by a thicker material section of the tarpaulin device, for instance. Furthermore, the reinforced section may be provided by adding another material which comprises stronger material characteristics than the material of the tarpaulin device. Thus, the life-time of the whole tarpaulin device may be increased because the adjustable openings are the most critical parts for breaking down. Thus, when reinforcing the critical locations, i.e. the adjustable openings of the tarpaulin device, the overall life-time of a tarpaulin device may be increased. 
     According to a further exemplary embodiment of the tarpaulin device, a plurality of adjustable openings may be provided. Thus, a high flexibility of a variety of different functional elements, such as transportation fixtures or mounting bracket devices, may be provided. Thus, the tarpaulin device may be used for a variety of different tower sections and different kinds of functional elements repeatedly. 
     According to a further exemplary embodiment, a connecting element for connecting the tarpaulin device to the tower section may be provided. The connecting element may comprise a thread eye in the tarpaulin device or an ear in the tower section. Furthermore, the tarpaulin device may comprise at its edges a connecting wire. The edges of the tarpaulin device may be wrapped over the flanges or edges of the tower section and then fixed with a rope, for instance. Furthermore, the connecting element of the tarpaulin device may comprise an elastic material, so that the tarpaulin device may be wrapped over the tower sections, so that the elastic material stretches and a press fit connection is provided. 
     According to a further exemplary embodiment of the method, the tarpaulin device is attached to the tower section of the wind turbine and the functional element is mounted to the tower section in the region of the adjustable opening. Thus, the tower sections may first of all covered with the tarpaulin device before being mounted to a functional element, such as a bracket device for transportation. Thus, when storing the tower section before transportation, dirt prevention may be provided. In praxis, before transporting the tower section, the tower section is often times stored for weeks or months. During this time period the tarpaulin device may already provide protection against dirt. When the tower section is finally transported, the functional elements, such as the transporting bracket devices may be fixed to the tower section. Therefore, the adjustable openings of the tarpaulin device may adjustably be opened and adapted to the length and to the contact location may be adjusted. 
     With the present invention tarpaulins with adjustable openings are provided wherein the adjustable openings may be located in the areas where the tower sections are mounted to transporting bracket devices and to lifting components, for instance. The adjustable openings may be opened and closed by Velcro elements, for instance. Thus, the adjustable openings may be adjusted very precisely to the bracket devices which are to be mounted onto the tower sections. The present invention may also comprise a plurality of adjustable openings that may be covered by a plurality of flap elements and sub flap elements. Hence, the tarpaulin element provides a more precise adjustable opening and is also more stable, because the openings will not be torn larger by the wind force during transportation, for instance. Furthermore, less cleaning of the inside of the tower sections is necessary after the transportation due to a better fitting of the adjustable openings to the functional elements, for instance. Moreover, by providing the adjustable openings, the tarpaulins may also be reused for other transportation unit or for other tower sections. 
     It has to be pointed out that of course any combination of features relating to different subject matters is also possible. 
     It has to be noted that embodiments of the invention have been described with reference to different subject matters. 
     In particular, some embodiments have been described with reference to apparatus type claims whereas other embodiments have been described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the apparatus type claims and features of the method type claims is considered as to be disclosed with this application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in more detail hereinafter with reference to the examples of embodiments but to which the invention is not limited: 
         FIG. 1  shows a conventional tarpaulin for a tower section; 
         FIG. 2  shows a schematic view of a tarpaulin device according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The illustration in the drawing is schematically. It is noted that in different figures, similar or identical elements are provided with the same reference signs or with reference signs, which are different from the corresponding reference signs only within the first digit. 
       FIG. 2  illustrates an exemplary embodiment of the present invention. A tarpaulin device  100  for a tower section  110  of a wind turbine is provided. The tarpaulin device  100  comprises an adjustable opening  200 . A location and a size of the adjustable opening  205  in the tarpaulin device  100  are adaptable to a functional element  101  of the tower section  110 . 
       FIG. 1  illustrates a conventional tarpaulin device  100 . The tarpaulin device  100  is wrapped over an open end of the tower section  110 . Through the tarpaulin device  100 , functional elements  101  are extending. The openings for the functional elements  101  are cut for instance by a sharp tool, such as a knife. As can be seen from  FIG. 1 , the openings respectively the tarpaulin cuts  102  are not adjusted to the functional elements  101  precisely. Thus, space is provided through which dirt may be entered into the inside of the tower section  110 . As can furthermore be seen from the cut tarpaulin device  100 , the tarpaulin cut  102  may be torn off unintentionally for instance by a wind force. 
       FIG. 2  illustrates an exemplary embodiment of the present invention. The tarpaulin device  100  comprises rib sections  201  and flap elements  202  that may provide the adjustable openings  205 . Through the adjustable openings  205  the functional elements  101  extend. Inside the tarpaulin device  100  the tower section  110  is located. The rib sections  201  are shown exemplary in a closed position in  FIG. 2 . The rib sections  201  may be closed by a Velcro element  204 , for instance. Also bottom stay elements or zip fastener elements may be used. 
     Furthermore,  FIG. 2  illustrates a plurality of flap elements  202 . Each of the flap elements  202  may open and close the adjustable opening  205  e.g. by Velcro elements  204 . The plurality of sub flap elements  203  may flexibly cover the adjustable openings  205 , so that the tarpaulin device  100  may be flexibly adjusted with its adjustable openings  205  to a variety of different shaped functional elements  101 . 
     As can be seen from  FIG. 2 , the functional elements  101  may comprise transporting elements that extend through tarpaulin device  100  upwardly, so that e.g. a crane may lift the tower section  110 . At the base section of the tarpaulin device  100  the flap element  202 , i.e. the sub flap elements  203 , may be opened individually, so that for instance a mounting bracket may be connected to the tower section  110 . Furthermore,  FIG. 2  furthermore illustrates a flap element  202  in a closed position of the tarpaulin device  100 . 
     It should be noted that the term “comprising” does not exclude other elements or steps and “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims. 
     LIST OF REFERENCE SIGNS 
     
         
           100  tarpaulin device 
           101  functional element 
           102  tarpaulin cut 
           110  tower section 
           201  rip section 
           202  flap element 
           203  sub flap element 
           204  Velcro element 
           205  adjustable opening