Abstract:
An apparatus for performing a supporting and/or a lifting operation to a wind turbine component inside the wind turbine nacelle is provided. The apparatus comprises at least a tool which comprises a manually operated linear actuator and a mounting device of said linear actuator in an element of the nacelle frame so that said linear actuator can be duly located with respect to the wind turbine component for performing said supporting and/or lifting operation.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to lifting tools for wind turbines and more particularly to manual lifting tools. 
     Wind turbines are devices that convert mechanical energy to electrical energy. A typical wind turbine includes a nacelle mounted on a tower housing a drive train for transmitting the rotation of a wind rotor to an electric generator and other components such as a yaw drive which rotates the wind turbine, several controllers and a brake. The wind rotor comprises a rotor hub supporting a number of blades extending radially therefore capturing the kinetic energy of the wind and causing the drive-train rotational motion. 
     Wind turbines are designed to ensure that their main components have a long working life, which means that regular maintenance work on the parts subject to greatest wear shall be carried out. Some of these components, particularly the generator, the gearbox, the rotor and the transformer, are extremely heavy and therefore require the use of a crane for handling. 
     Bearing in mind the strict limitations regarding maintenance work, given that wind turbines are installed in tall towers and built in, generally, in solitary areas, the use of external cranes leads to problems of availability and cost. 
     To face these problems wind turbines can be provided with internal cranes to carry out maintenance work on their heavier components without the need for external resources. 
     For example U.S. Pat. No. 7,748,547 in the name of the applicant discloses a movable independent crane system that can be used temporarily for mounting, moving or replacing components of wind turbines. 
     When a maintenance work shall be carried out when the wind turbine is de-energized or in commissioning mode, internal cranes needing an electric supply cannot be used so that there is a need of lifting tools that can operate in these situations for performing a variety of maintenance works. 
     BRIEF DESCRIPTION OF THE INVENTION 
     An object of the present invention is to provide an apparatus which does not need an electric supply for performing in a wind turbine maintenance works that require supporting and/or lifting wind turbine components. 
     Another object of the present invention is to provide a method for performing maintenance works in a wind turbine which require supporting and/or lifting wind turbine components without using electric-dependant means. 
     In one aspect, these and other objects are met by an apparatus for performing a supporting and/or a lifting operation to a wind turbine component inside the wind turbine nacelle, the apparatus comprising at least a tool which comprises a manually operated linear actuator and a mounting device of said linear actuator in an element of the nacelle frame so that said linear actuator can be duly located with respect to the wind turbine component for performing said supporting and/or lifting operation. 
     In one embodiment, said manually operated linear actuator is a power screw linear actuator. Power screw linear actuators are suitable means for performing maintenance works in wind turbine components that require small vertical displacements such as, for example, the replacement of the feet of the wind turbine transformer or the opening of a door in the roof of the nacelle. 
     If needed, the power screw linear actuator further comprises a torque reducer to decrease the input torque requirement to a manually feasible level. Suitable manual operating means of the linear actuator are particularly a hand crank or a portable drill. 
     In one embodiment addressed to perform supporting and lifting operations, the apparatus further comprises an attachment arm with the wind turbine component coupled to the linear actuator through, particularly, coupling means which allow a rotation of the attachment arm with respect to the linear actuator. 
     In one embodiment, the mounting device of the linear actuator comprises two wedges to be joined to an element of the nacelle frame and a supporting plate of the linear actuator; each wedge comprising a back part and a front part with respect to the wind turbine component configured to be joined so that the element of the nacelle frame can be clamped between them; said supporting plate being configured to be joined to the front part of said two wedges. This mounting device allows, on the one hand, a good orientation of the linear actuator with respect to the wind turbine component and, on the other hand, a firm grip of the linear actuator to said element of the nacelle frame which is, typically, an I-shaped beam. 
     In one embodiment, the apparatus comprises two tools, each of them comprising a manually operated linear actuator and a mounting device of said linear actuator in an element of the nacelle frame. Therefore the apparatus acts over two points of the wind turbine component facilitating its manual operation and also an improved control of the lifting operation. 
     Advantageously, an apparatus comprising two tools further comprises a drive shaft connecting both linear actuators so that their manual operation can be synchronized. 
     In another aspect, the above mentioned objects are met by a method for supporting and lifting a wind turbine component, comprising the following steps: 
     a) providing an apparatus comprising two tools, each of them comprising a manually operated linear actuator having an attachment arm with the wind turbine component coupled to it and a mounting device of said linear actuator in the nacelle frame; 
     b) installing said tools in elements of the nacelle frame so that said linear actuators are duly positioned with respect to the wind turbine component for performing said supporting and lifting operation; 
     c) attaching said wind turbine component to said tools; 
     d) performing the lifting operation of said wind turbine component operating manually said linear actuators. 
     This method can be used, for example, for supporting and lifting the wind turbine transformer when their feet are being replaced. 
     In another aspect, the above mentioned objects are met by a method for lifting a wind turbine component, comprising the following steps: 
     a) providing an apparatus comprising two tools, each of them comprising a manually operated linear actuator and a mounting device of said linear actuator in the nacelle frame; 
     b) installing said tools in elements of the nacelle frame so that said linear actuators are duly positioned with respect to the wind turbine component for performing said lifting operation; 
     c) performing the lifting operation of said wind turbine component operating manually said linear actuators. 
     This method can be used for example for lifting a door on the roof of the nacelle for allowing the access to it from the outside to, for example, an external crane. 
     Other desirable features and advantages of the invention will become apparent from the subsequent detailed description of the invention and the appended claims, in relation with the enclosed drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a wind turbine nacelle with the roof in an open position. 
         FIGS. 2 a  and 2 b    are perspective views of a tool of an apparatus according to the present invention installed on an I-shaped beam. 
         FIGS. 3 a  and 3 b    are, respectively, side and plan views of the linear actuator of a tool of an apparatus according to the present invention. 
         FIGS. 4 a  and 4 b    are respectively side and plan views of an apparatus according to the present invention comprising two tools and a synchronizing drive shaft. 
         FIG. 5 a    is a perspective view of an apparatus according to the present invention installed on I-shaped beams having attached to it a wind turbine transformer and  FIG. 5 b    is an enlarged view showing one of tools of the apparatus. 
         FIG. 6 a    is perspective view of a wind turbine nacelle having installed an apparatus according to the present invention for lifting a door of the nacelle roof and  FIG. 6 b    is an enlarged view of a tool of said apparatus installed on an I-shaped beam. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the nacelle  11  of a wind turbine that houses a gearbox  21  and a generator  23  driven by a shaft coupled to a rotor hub  25  and a transformer  27  supported by the nacelle frame  29 . The nacelle frame  29  also includes a supporting structure of a gantry crane  31  formed by vertical and horizontal I-shaped beams  33 ,  35  which is used for performing mounting/dismounting operations of wind turbine components. The roof  37  of the nacelle  11  is shown in an open position. 
       FIGS. 2 a  and 2 b    show an apparatus comprising a tool  40  that can be used temporarily for supporting and/or lifting a wind turbine component installed in an I-shaped beam  35  belonging to the nacelle frame  29 . The tool  40  comprises a manually operated linear actuator  41  with an attachment arm  43  and a mounting device  61  configured for mounting said linear actuator  41  in said I-shaped beam  35 . 
     The tool  40  can be used as a temporary support means of a wind turbine component attached to it by means of the attachment arm  43  for performing on it a maintenance operation that requires removing its normal supporting means. In this case the linear actuator  41  acts as a simple load path of the weight of wind turbine component to the I-shaped beam  35 . 
     The tool  40  can also be used as a lifting means of a wind turbine component attached to it by means of the attachment arm  43  using the linear actuator  41  for the lifting operation. 
     The tool  40  can also be used both as a temporary support means and as a lifting means of a wind turbine component. 
     In the embodiment shown in  FIGS. 2 a , 3 a  and 3 b    the linear actuator  41  comprises a power screw linear actuator  45 , a torque reducer  47  and a hand crank  49 . 
     The driving torque generated by a manual operation of the hand crank  49  is transferred to the power screw linear actuator  45  through the torque reducer  47  causing a linear displacement of its screw  51  to perform a lifting operation. As illustrated in said Figures the power screw linear actuator  45  is configured for lifting operations of a short run. 
     The only difference between  FIGS. 2 a  and 2 b    is that the operation means of the power screw linear actuator  45  is a hand crank  49  in the first case and a portable drill  53  in the second case. 
       FIGS. 2 a  and 2 b    also show a drive shaft  55  coupled to the tool  40  which, as will be explained later on, is used in a device comprising two tools  40 . 
     The mounting device  61  comprise two wedges  63 ,  63 ′, each of them formed by a back part  65 ,  65 ′ and a front part  67 ,  67 ′, and a supporting plate  69  for the tool  40  to be attached to the front parts  67 ,  67 ′ of the two wedges  63 ,  63 ′. 
     The configuration of the two edges  63 ,  63 ′ is adapted to the I-shape of the supporting beam  35 . The back and front parts  65 ,  65 ′;  67 ,  67 ′ include cooperating recesses  70  with the flanges  68  of the beam  35  so that they can be clamped to the beam  35  and joined between them by means of, for example, bolts. 
     The power screw linear actuator  45  comprises a base  54  as attaching means to the supporting plate  69  of the mounting device  61 . 
       FIGS. 4 a  and 4 b    show an apparatus  38  that can be used temporarily for supporting and/or lifting a wind turbine component comprising two tools  40  to be installed in two distant places of the nacelle frame to act over the wind turbine component in two distant places. 
     The apparatus  38  further comprise a drive shaft  51  coupled to the shafts of the tools  40  for synchronizing the lifting operation. 
       FIGS. 5 a  and 5 b    show one of those apparatus with its tools  40  attached to a transformer  27  through attachment arms  43 . 
     The embodiment shown in  FIGS. 5 a , 5 b    is suitable, for example, for performing maintenance operations on the wind turbine transformer  27  that require, for example, a replacement of its feet. In that case the apparatus can be used for supporting and lifting the transformer  27  to the height required (usually a few mm) for replacing the transformer feet. 
       FIGS. 6 a  and 6 b    show one of those apparatus with its tools  40 ′ acting temporarily over a roof door  80  so that the transformer  27  can be removed from the nacelle  11 . 
     The apparatus comprises two tools  40 ′ installed in two I-shaped beams  35  of the nacelle frame  29  comprising linear actuators  41 ′ and mounting devices  61 ′. 
     The linear actuators  41 ′ have a similar configuration than the linear actuators  41  of the above-mentioned tools  40  with the exception that they do not comprise the attachment arm  43  because the linear actuators  41 ′ act directly as operation arms over the roof door  80 . On the other hand, the linear actuators  41 ′ shall be configured for a larger run than the linear actuators  41 . 
     The mounting devices  61 ′ are identical to the mounting devices  61  of the above-mentioned tools  40 . 
     The heaviest part of the above mentioned tools  40 ,  40 ′ may have a weight of about 30 Kg so that its installation in the wind turbine does not raise any problem. 
     An important advantage of this invention is that provides a manually operated multi-functional apparatus to perform supporting and/or lifting operations of wind turbine components as an alternative to internal/external cranes particularly when the wind turbine is de-energized or in commissioning mode and also as a complementary means to said cranes for certain maintenance operations. 
     Although the present invention has been described in connection with various embodiments, it will be appreciated from the specification that various combinations of elements, variations or improvements therein may be made, and are within the scope of the invention.