Abstract:
A wind turbine is provided. In another aspect, a hubless or hollow wind turbine includes a hubless and/or hollow alternator or generator. A further aspect employs a hubless and/or hollow wind turbine surrounding an elongated member such as a pre-existing structure. In yet another aspect, a hubless and/or hollow wind turbine employs a directly driven alternator or generator.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/180,157, filed on May 21, 2009, which is incorporated by reference herein. 
     
    
     BACKGROUND AND SUMMARY 
       [0002]    The disclosure relates generally to wind turbines and more particularly to a wind turbine mounted and rotating around an elongated structure. 
         [0003]    Many varieties of wind turbines are known. For example, it is common to employ a vertical mast with a horizontally extending axial hub around which rotates three elongated blades. These devices, however, are unsightly, noisy, require unique and dedicated mast structures, and need a large rotational clearance area for the blades. 
         [0004]    A hubless wind turbine is disclosed in International PCT Patent Publication No. WO 2008/109784 entitled “Hubless Windmill” published to Condoor et al. on Sep. 12, 2008, which is incorporated by reference herein. This wind turbine, however, employs a complicated ring gear and indirectly driven generator configuration which are disadvantageously positioned to obstruct central mounting of the windmill. They also obstruct use of blades that are axially elongated but have radial depth. Furthermore, the practical mounting of this device is not disclosed despite the importance of such for real-world application. 
         [0005]    Other vertical axis wind turbines and horizontal axis wind turbines have been experimentally attempted. Such devices typically employ a central hub as the rotational axis. One such example is disclosed in U.S. Pat. No. 6,309,172 entitled “Wind Turbine with Low Vertical Axis” which issued to Gual on Oct. 30, 2001, and is incorporated by reference herein. Nevertheless, it “is difficult to mount vertical-axis turbines on towers, meaning they are often installed nearer to the base on which they rest, such as the ground or a building rooftop. The wind speed is slower at a lower altitude, so less wind energy is available for a given size turbine. Air flow near the ground and other objects can create turbulent flow, which can introduce issues of vibration, including noise and bearing wear which may increase the maintenance or shorten the service life.”  Wind Turbine, Wikipedia , (Apr. 30, 2009). 
         [0006]    In accordance with the present invention, a wind turbine is provided. In another aspect, a hubless and/or hollow wind turbine includes a hubless or hollow alternator or generator. A further aspect employs a hubless and/or hollow wind turbine surrounding an elongated member such as a pre-existing structure. In yet another aspect, a hubless and/or hollow wind turbine employs a directly driven alternator or generator. Moreover, another aspect provides a vertical axis wind turbine including modularly stacked rotatable sections capable of rotating at different speeds. An additional aspect provides a hubless and/or hollow wind turbine mounted to a multi-functional, elongated structure which also supports a water tower reservoir, a power transformer or an overhead wire connected to a generator of the wind turbine. A method of assembling a wind turbine to an elongated structure is also provided. Furthermore, a method of operating a hubless and/or hollow wind turbine is disclosed. 
         [0007]    The wind turbine of the present application is advantageous over conventional devices such that the present wind turbine is considerably more aesthetically pleasing, more compact in packaging size, integrated onto pre-existing structures and has reduced operating noise. The present wind turbine also advantageously has a less complex and direct drive transmission and/or allows for differing speeds between adjacent modularized units. Furthermore, there are cost and space utilization advantages of mounting the present wind turbine around an existing pole, tower or the like. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side elevational view showing the present wind turbine mounted to a water tower; 
           [0009]      FIG. 2  is a side elevational view showing the wind turbine mounted to a portion of a pole; 
           [0010]      FIG. 3  is a perspective view showing the wind turbine mounted to the pole; 
           [0011]      FIG. 4  is a perspective view showing the wind turbine, with outer covers removed, mounted to the pole; 
           [0012]      FIG. 5  is a diagrammatic bottom view showing the inner blades and outer wind diverters of the wind turbine; 
           [0013]      FIG. 6  is a partially cross sectional view, taken along line  6 - 6  of  FIG. 5 , mounted to the pole; 
           [0014]      FIG. 7  is a perspective view showing the inner blades and a generator of the wind turbine; 
           [0015]      FIG. 8  is a side elevational view showing the inner blades and generator of the wind turbine; 
           [0016]      FIG. 9  is a top diagrammatic view showing the inner blades of the wind turbine; 
           [0017]      FIG. 10  is a perspective view showing the outer wind diverters of the wind turbine; 
           [0018]      FIG. 11  is a side elevational view showing multiple modularized wind turbine units mounted to a water tower; 
           [0019]      FIG. 12  is a front elevational view showing an electricity transmission system including the pole, the wind turbine and transformers; 
           [0020]      FIG. 13  is a cross-sectional view, taken perpendicular to that of  FIG. 6 , showing a hubless and hollow generator, employed in the wind turbine; 
           [0021]      FIG. 14  is a diagrammatic top view showing another embodiment of the wind turbine; 
           [0022]      FIG. 15  is a partially fragmentary, perspective view showing another embodiment of the wind turbine; and 
           [0023]      FIG. 16  is an enlarged and fragmentary cross-sectional view showing the wind turbine embodiment, taken along line  16 - 16  of  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    One embodiment of a wind turbine system  21  is shown in  FIG. 1 . Wind turbine system  21  includes a wind turbine  23  mounted to a generally middle section of a vertically elongated structure  25  such that the wind turbine is entirely elevated off of the ground by at least ten feet and with this configuration by at least 40 feet. Structure  25  is multi-functional by also serving to support a public utility device such as a water tower reservoir  27  above the wind turbine. Accordingly, water pipes are internally carried within structure  25  and therefore also through the hollow center of wind turbine  23 . 
         [0025]    Referring now to  FIGS. 2-10  and  13 , wind turbine  23  is shown mounted onto another embodiment of a vertically elongated structure  29 , in this situation a solid telephone or video communications pole, electrical pole or other similar type of structure. Wind turbine  23  includes a set of inner wind-driven blades or airfoils  31 , a set of outer blades or wind diverters  33 , a generator  35 , upper mounting brackets  37 , lower mounting brackets  39 , and upper and lower covers  41  and  43 , respectively. At least ten, and with this configuration at least thirty-four, inner blades  31  are fixed to an annular base  51  and an opposite annular ring  53 . A circular ball bearing track, self-lubricating Rulon plane bearing (from TriStar Plastics Corp.), or opposed magnetic anti-frictional bearing track  55  is disposed between base  51  and an adjacent structural and stationary, annular platform  57  to allow the set of inner blades to freely rotate around a central vertical axis  59 . Optionally, similar bearing tracks may be employed for rings  51  and  53 . 
         [0026]    Each inner blade  31  preferably has an airfoil or arcuate cross-sectional shape, such as disclosed in the Gual U.S. Pat. No. 6,309,172, however, other shapes can alternately be employed although performance may not be as desirable. It is envisioned that inner blades  31  are extruded from aluminum or made with an outer aluminum sheet adhered over a honeycomb-type of laminated core. Alternately, a fiber filled polymeric or carbon fabric composite can be used, or an injection molded polymer can be employed for small scale blades. Each inner blade  31  is elongated in a generally vertical direction substantially parallel to axis  59 , however, it is envisioned that helically shaped, diagonally elongated or other such blade configurations can also be employed as long as they are somewhat elongated in the direction of axis  59 . 
         [0027]    The set of outer diverter blades  33  remains generally stationary during normal use and concentrically surround inner blades  31 . The inner and outer sets of blades are coaxially oriented to generally surround the adjacent portion of structure  29  and axis  59 . It is alternately envisioned that outer blades  33  may be manually or automatically rotated or moved from a closed position to an open position, or between different wind directing positions, but are otherwise not intended to rotate around axis  59 . At least ten, and more preferably at least thirty-four, outer blades are employed to hide the inner blades and adjacent portion of the structure. Furthermore, outer blades  33  act as wind diverters to direct the wind at desired angles into wind turbine  23  so as to most efficiently act upon and rotate inner blades  31  about central axis  59 . Outer diverter blades  33  further reduce drag otherwise caused by the wind flowing to the opposite side of the internal blades  31 . If the outer blades are spaced close enough, they may additionally reduce the risk of undesired bird or human limb entry into wind turbine. An outer or inner mesh grating, fence or air permeable fabric  61  (see  FIG. 12 ) can optionally surround the set of outer blades to further camouflage the inner blade rotation and reduce undesired bird, insect, human limb and ice insertion. Alternately, the mesh may be located between the inner and outer sets of blades. Each outer blade  33  is elongated generally parallel to axis  59  but they may alternately have a helical, diagonal or other somewhat offset configuration. The outer blades are preferably manufactured out of the same materials as with the inner blades. Alternately, an elongated protective structure like hollow capillary tubes or a honeycomb structure is used to guide the wind straight at the inner blades. 
         [0028]    Outer blades  33  are secured between platform  57  and an opposite platform  71 . Steel or aluminum, or alternately composite or polymeric, diagonal or angle iron brackets  35  and  39  serve to stationarily secure platforms  71  and  57 , respectively, to structure  29  by way of screws, rivets, welding or gluing. Aluminum, polymeric or composite covers  41  and  43  are removably fastened to the ends of the wind turbine unit, and each have a frusto-conical shape. 
         [0029]    Generator or alternator  35  has an annular and hollow configuration, and includes an annular and hollow stator  73 , and an annular and hollow armature  75  disposed concentrically therein. Armature  75  employs a magnet and is frameless, hubless and brushless. One or more upstanding brackets extending from rotatable armature  75  are directly coupled to rotatable base  51  which holds wind-driven inner blades  31 ; this provides a direct drive and solid coupling therebetween such that the rotating section of the generator is essentially integrated into the inner blade and base assembly of the wind turbine to move together as a single unit. Armature  75  is directly fastened to base  51  via tapped holes in the top of the armature and bottom of the base, clear of the central and hollow throughbores. Armature  75  has a rotational axis aligned with inner blade rotational axis  59  and armature  75  rotates around the outside of structure  29  during operation. This provides a well balanced rotational unit in combination with the set of inner blades thereby reducing undesirable binding, cocking and off-axis moment arms otherwise found with some conventional devices. The stator consists of an external housing made of an aluminum alloy bearing magnetic laminations, electrical windings, power cabling and thermal sensor cabling. The winding heads are encapsulated in a resin for protection and to decrease thermal resistance. The armature or rotor consists of a structure used as a magnetic yoke on which multiple magnets are fixed. The magnets are originally phosphatized and additionally coated with an anti-corrosion varnish, and thereafter protected from corrosion by grease. An acceptable generator can be obtained from Alxion of Colombes, France, as Model 300 STK, however, its central rotoric flange and hub must be removed to provide a hubless and hollow center, and its inside diameter will likely need to be increased. Generator stator  73  is stationarily coupled to an underside of platform  57 . It is alternately envisioned that the stator and armature positions can be reversed so the armature moves about the outside and the stator is inside. 
         [0030]    Referring to  FIG. 14 , a different blade configuration is shown for another embodiment of a hollow wind turbine  123 . Seven generally straight guide vanes or blades  133  are located on a stator section  157 , with each guide vane  133  having a tapered leading edge. Each guide vane  133  has a radially offset angle θ equal to or between 25°-60°, and optimally approximately 45° relative to a radial line through the vertical rotational axis. 
         [0031]    Six inner wind-driven blades  131  are mounted to a rotor section  151  for rotation about a hollow central tube  152  disposed circumferentially around a vertical utility or water carrying pole or structure  129 . Each inner blade  131  has an airfoil cross-sectional shape with a thicker leading end being slightly outboard more than the thinner trailing end, but the thickness difference being less than half the cross-section length of an inner blade. The inner blades are arranged in ganged pairs with a greater circumferential spacing between pairs than between the inner blades of each pair. The angle a of the leading inner blade of each pair relative to a radial line is equal to or between 40°-60° and optimally approximately 50°, and the angle β of the trailing inner blade of each pair relative to a radial line is equal to or between 40°-60° and optimally approximately 60°. 
         [0032]    Furthermore, central pole  129  advantageously enhances the self-start up rotational performance of wind turbine  123  by creating a downstream wake to disrupt static equilibrium air flow forces otherwise created inside the turbine. Thus, a utility pole having a diameter of at least 8 cm (such that the outside diameter of pole  129  is at least 25% of the outside diameter of the set of inner blades  131 ), and more desireably greater than 20 cm, is expected to improve air flow characteristics and rotational efficiencies. The use of a tube  152  mounted to a stationary base of the wind turbine should provide similar self-start up advantages but with a more consistent and smoother (or patterned) surface than a pole made of rough wood or the like. The tube also provides improved modularized pre-assembly of the wind turbine for later final assembly onto an existing pole. 
         [0033]      FIGS. 15 and 16  illustrate the directly driven and integrated construction of the generator with wind turbine  123 . As with the embodiment of  FIGS. 6-8 , the present embodiment has a concentrically annular, hollow and hubless stator  173  and armature  175 . Stator  173  is mounted to stationary platform  157  holding vanes  133 . Armature  175  rotates with base  151  as a single piece or directly coupled subassembly, and base  151  holds and rotates with inner blades  131  about tube  152  and central post  129 . Stator  173  and the magnetic segment of armature  175  have approximately the same vertical dimension and they have a vertical electromagnetic and mechanical interface throughout their facing circumferences as viewed in cross-section. 
         [0034]      FIG. 15  further shows another configuration of inner blades  131  and outer diverter blades or vanes  133 . In this embodiment there are twelve inner blades and fourteen diverter vanes  133 , each being oriented in a direction closer to a radial line through the central axis than to circular lines intersecting all of the inner or outer blades. Each of blades  131  and  133  may optionally be manually, mechanically or electromagnetically rotated about its own axis to take advantage of different angular air flow characteristics, such as between initial startup and high speed operation. 
         [0035]    It is alternately envisioned that generator  35  (see  FIGS. 2 and 6 ) can be below, above, or duplicated above and below, the rotating inner blades. Furthermore, an alternate variation advantageously uses the permanent magnets of the rotor in combination with a magnetic bearing; thus, the magnet of the generator serves multiple purposes to reduce weight, and to minimize the mechanical friction and durability concerns of traditional bearings. 
         [0036]    In one construction, wind turbine  23  is preassembled as two or more sub-assemblies or sub-units  23   a  and  23   b  (see  FIG. 4 ). The major subassembly components are likewise subdivided. Thereafter, each sub-unit is located against a corresponding side of a pre-existing structure and then the sub-units can be fastened together through bolts, rivets, welding or the like. The entire wind turbine unit is also affixed to the structure before, after or during assembly of the two or more sub-units together. This allows for the present wind turbine to be attached to existing water towers, poles and other structures preattached to the ground, a building or the like. It is further envisioned that the unit can be subdivided into halves, thirds or other subsections for assembly onto a pole or tower. In another construction, the entire wind turbine unit is preassembled as a single unit with a hollow and hubless center. It is thereafter slid onto a new, elongated structure or one with an open end, until the mounting brackets reach their desired locations and are securely fastened thereto. 
         [0037]    A modularized configuration of a wind turbine system  91  is shown in  FIG. 11 . In this embodiment, two or more modularized, wind turbine units  93  and  95  are stationarily attached to an elongated structure  97  such as a water tower, pole or the like. This allows for the inner blades to be rotated at independent and different speeds depending on the wind speed characteristics at different elevations off of the ground. Alternately, the different units can be counter-rotated opposite each other to balance rotational movement by cancelling inner blade torque on the assembly. Each wind turbine unit has its own associated hubless and hollow generator. The structure mounting bracketry and covers can be integrated, combined or unnecessary at adjacent interfaces but each wind turbine unit is otherwise the same as previously described hereinabove. 
         [0038]      FIG. 12  shows an alternate embodiment wind turbine system  101 . In this construction, a wind turbine  103 , like that described with regard to  FIG. 6 , is mounted to a pole structure  105  carrying overhead electricity or communications wires. One or more electrical power transformers  107  are also affixed to structure  105  and are electrically connected to a hollow and hubless generator  109  of the type previously described hereinabove. Generator  109  and/or transformers  107  are electrically connected to the overhead electricity carrying wires  111 . It is also noteworthy that structure  105  is carrying electrical wires between multiple other structures  113  or buildings. Thus, structure  105  is serving a multi-functional purpose rather than requiring a dedicated and unique wind turbine mast as with conventional devices. 
         [0039]    While various embodiments have been described herein, it should be appreciated that variations may be made without departing from the present invention. For example, vertically elongated structures have been shown, however, diagonally or horizontally elongated structures may be employed with the present hubless and hollow wind turbine assemblies although all of the disclosed advantages may not be fully realized. Furthermore, additional wind diverters, external and/or internal to the inner rotating blades, may be employed to provide desired air flow characteristics depending upon the specific end use application, environmental conditions and generator cooling requirements. Moreover, a dedicated structural pole or tower can be employed to extend through an otherwise hollow wind turbine, however, the multifunctional cost and aesthetic benefits may not be achieved. It should also be appreciated that certain aspects of the present wind turbine may be used without the preferred generator, although various advantages may be lost. As another alternate embodiment, a small sized wind turbine can be mounted on a portable pole which can be temporarily hand carried and stuck in the ground for powering a motor home or the like; such a configuration has a reduced quantity of inner and outer blades but optimally at least six of each. While various materials have been disclosed, other materials may alternately be employed as long as the disclosed function is achieved. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.