Patent Application
20100006710
1. Technical Field
The subject matter described here generally relates to wind turbines, and, more particularly, to a cable bridge for a wind turbine tower.
2. Related Art
A wind turbine is a machine for converting the kinetic energy in wind into mechanical energy. If the mechanical energy is used directly by the machinery, such as to pump water or to grind wheat, then the wind turbine may be referred to as a windmill. Similarly, if the mechanical energy is converted to electricity, then the machine may also be referred to as a wind generator or wind power plant.
Wind turbines are typically categorized according to the vertical or horizontal axis about which the blades rotate. One so-called horizontal-axis wind generator is schematically illustrated in
The wind turbine tower 4 is typically constructed by rolling arcuate sheets of steel and securing the end of those sheets together to form closed rings. The rings are then stacked on top of each other to form the length of the tower. These rings typically have different thicknesses, with the plates getting thinner toward the top of the tower. The rings may also have different shapes, changing from cylindrical to conical as one moves up the tower. Due to the large size of the finished tower 4, and the logistical constraints against transporting such a large structure, it is impractical to assemble the entire tower 4 before it is shipped to the installation site. Therefore, as discussed in commonly-owned co-pending U.S. application Ser. No. 11/969,463 (Attorney Docket No. 229524) for “Wind Turbine Tower Joints,” multiple, prefabricated ringed tower wall sections will often be shipped and then welded and/or flanged to each other at various joints 20 in wall of the tower 4.
As illustrated in the partial interior view of the tower 4 shown in
The joints 20 with flanges internal to the tower 4 obstruct the routing of the cables 24. Also, due to the need to service these flanged connection at joints 20 between the towers wall sections, the cables 24 in the vicinity of the joints must be supported in a manner that will allow access to the flange bolts behind the cables. The difficulty of temporarily repositioning these cables 24 is often compounded by the fact that the cables are tied or otherwise secured to cable trays or raceways attached to the walls of the tower 4 with little slack. Furthermore, pre-installed cables 24 may require connections to complete the circuit. Those connections must typically be crafted inside an electrical enclosure, such as a junction box, which increases the time and cost associated with completing the circuit and/or repositioning the cables 24.
These and other drawbacks associated with such conventional approaches are addressed here in by providing, in various embodiments, a wind turbine including a tower having at least one joint; at least one cable extending across the at least one joint; and a cable bridge for supporting the at least one cable over the at least one joint.
Various aspects of this technology will now be described with reference to the following figures (“FIGs.”) which are not necessarily drawn to scale, but use the same reference numerals to designate corresponding parts throughout each of the several views.
In
In the illustrated examples, the ends of the arms 52 are configured as blades for fitting into channels in the cable trays or raceways arranged at each end of the cable bridge 50. The blades at the ends of the arms 52 are then bolted to the cable trays or raceways on the wall of the tower 4. However, the cable bridge may be secured to the cable trays or raceways and/or wall of the tower 4 in other ways.
Each of the illustrated parallel arms 52 has at least one hinge 56 for articulating the corresponding arm relative to the wall of the tower 4. However, additional hinges may also be provided for improved positioning of the cable bridge 50. For example, two or more hinges may be provided for allowing different sections of the arms 52 between hinges 56 to articulate substantially independently. Each of the arms 52 in the illustrated examples includes four hinges 56 that rotate about parallel horizontal axes. With four hinges 56, at least one section of each arm 52 extending between two of the hinges 56 may be arranged substantially parallel or tangential to the wall of the tower 4 in order to increase clearance between the cables 24 and the wall of the tower 4.
The hinges may also be arranged to rotate about other axes, including non-horizontal axes, and the rotational axes of the hinges 56 do not necessarily need to be parallel to each other for any single arm or pair of arms, or co-linear between pairs of arms. The hinges 56 may also be provided with additional degrees of freedom so as to rotate, and/or partially rotate, about other axes. The arms 52 may also be extendable, such as in a telescopic fashion.
In the illustrated examples, the ends of the ends of the hinges 56 are configured as blades for fitting into channels in the straight sections of the arms 52 between the hinges. The blades at the ends of the hinges 56 are then bolted to the arms 52. However, the hinges 56 may be formed continuously with the straight sections of the arms 52 and/or fastened or secured in other ways.
In the examples illustrated here, the at least one support is configured as several rungs 54 extending between each section of the arms between hinges. Each arm section is configured as a channel for receiving a blade that extends from a hinge 56. However, the blades and channels may be reversed, and the blades may be fastened or otherwise secured to the channels in other manners.
One or more of the cables 24 is then secured to one or more of the rungs 54 in any conventional manner such as through the use of cable ties or cable cleats. The cables 24 may be supported on either side of the cable bridge 50. For example, some or all of the cables 24 may be arranged on different sides of the rungs 54 in different sections of the arms 52. However, the cables 54 may also he simply draped over one or more of the rungs 54 without securing and/or secured to the rungs 54 using other means besides cable ties or cable cleats.
In addition to rungs 54, the supports for the cables 24 may be configured as a plate, tray, net, mesh, or channel for supporting and/or securing one or more of the cables 24. For example, any such plate, tray, net, mesh or channel for carrying the cables 24 may be secured to the rungs 54 and/or secured to the arms 52 with the cables 24 merely resting in or on the support. The cables 24 may also be secured directly to the arms 52. The rungs 54 may also be formed in U- or V-shapes extending between the arms 52.
As illustrated in
The technology described above offers various advantages over conventional approaches. For example, when supported by the cable bridge 50, the cables 24 are not subjected to abrasion due to contact with the tower joint 20 such as may occur movement of the tower 4 during operation. The cable bridge 50 also protects the cables from damage stemming from activities conducted by personnel within the tower 4. In addition, the cable bridge 50 provides a safe location to arrange and splices, connectors, switchgear, and/or other electrical equipment that may be further protected by the cover 60 without the need for an electrical cabinet, junction box, or other protective barrier/enclosure. The cable bridge therefore also reduces the amount of time that it takes to assemble the tower. For example, the various hinges 56 in the arms 52 allow the cable bridge 50 to be easily configured to accommodate various tower and cable tray/raceway configurations.
It should be emphasized that the embodiments described above, and particularly any “preferred” embodiments, are merely examples of various implementations that have been set forth here to provide a clear understanding of various aspects of this technology. One of ordinary skill will be able to alter many of these embodiments without substantially departing from scope of protection defined solely by the proper construction of the following claims.
