Patent Publication Number: US-2016230744-A1

Title: Wind turbine with dual blade assemblies

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to wind turbines. More particularly, the present invention relates to a wind turbine having a pair of blade assemblies that rotate independently of each other. 
     BACKGROUND OF THE INVENTION 
     Green energy trends have been on the rise in recent years and, subsequently, so has the demand for consumer grade wind turbines for harvesting wind energy. Specifically, interest in wind turbines that can be utilized to provide power for individual homes and small businesses has increased greatly over recent years. However, individual home and business owners often face challenges that operators of large scale “wind farms” typically do not encounter. For example, because the wind turbine is necessarily located at the home or business to which energy is supplied, the amount of space that is available to operate the wind turbine may be limited. As well, the environmental conditions at the desired location may not provide the wind speeds that are required for efficient and reliable operation of traditional wind turbines. For example, the prevailing wind speeds of the desired location may be lower than the target wind speeds required for turbine cut-in with traditional wind turbines, cut-in referring to the wind speed at which the turbine blades begin to rotate and, therefore, generate energy. As well, low wind speeds are known to reduce the ability of existing wind turbines to approach the 59.3% limit of converting wind energy to electrical energy suggested by the Betz Limit. 
     The present invention recognizes and addresses considerations of prior art constructions and methods. 
     SUMMARY OF THE INVENTION 
     One embodiment of the present disclosure provides a wind turbine having a housing, a generator including a field magnet and an armature, the generator being rotatably disposed within the housing, a first blade assembly non-rotatably fixed to one of the field magnet and the armature of the generator, and a second blade assembly non-rotatably fixed to the other of the field magnet and the armature of the generator, wherein the first blade assembly rotates in a first direction with respect to the housing and the second blade assembly rotates in an opposite second direction with respect to the housing. 
     Another embodiment of the present disclosure provides a wind turbine having a housing, an electrical generation unit including a field magnet and an armature, the electrical generation unit being rotatably disposed within the housing, a first blade assembly non-rotatably fixed to one of the field magnet and the armature of the electrical generation unit, and a second blade assembly non-rotatably fixed to the other of the field magnet and the armature of the electrical generation unit. 
     Yet another embodiment of the present disclosure provides a wind turbine having a housing, an electrical generation unit including a field magnet and an armature, the field magnet and the armature each being rotatably disposed within the housing, a first blade assembly fixed to one of the field magnet and the armature of the electrical generation unit, and a second blade assembly fixed to the other of the field magnet and the armature of the electrical generation unit, wherein the field magnet and the armature are rotatable independently of each other. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which: 
         FIG. 1  is a perspective view of a wind turbine including a pair of blade assemblies in accordance with the present disclosure; 
         FIG. 2  is a front view of the wind turbine shown in  FIG. 1 ; 
         FIG. 3  is a side view of the wind turbine shown in  FIG. 1 ; 
         FIG. 4  is a partial, exploded view of the wind turbine as shown in  FIG. 1 ; 
         FIG. 5  is a cutaway, partial perspective view of the wind turbine shown in  FIG. 1 ; and 
         FIGS. 6A and 6B  are schematic diagrams of the wind turbine shown in  FIG. 1 . 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Referring now to  FIGS. 1 through 3 , a wind turbine assembly  100  in accordance with an embodiment of the present disclosure is shown. As shown, wind turbine assembly  100  includes a front blade assembly  150  that extends forwardly of a housing  110  of wind turbine assembly  100  and a rear blade assembly  160  which extends rearwardly of housing  110 . Housing  110  is pivotably secured to a tower  116  that extends upwardly from a corresponding support surface (not shown), housing  110  defining an interior compartment in which an electrical generation unit  120  ( FIG. 4 ) is disposed, as discussed in greater detail below. A yaw control mechanism  190  is disposed between housing  110  of wind turbine assembly  100  and tower  116 , which allows the wind turbine assembly to be pointed in the direction of the prevailing winds, as is commonly known in the art. A nacelle  102  is disposed aft of rear blade assembly  160  to provide improved aerodynamics for wind turbine assembly  100 . 
     Referring additionally to  FIG. 4 , front blade assembly  150  includes a central hub  152  from which a plurality of blades  151  radially extend, each blade  151  being secured to hub  152  by way of fasteners (not shown) passing through corresponding blade recesses  156 . Preferably, the pitch of each blade  151  may be altered, as is known in the art, to maximize the speed of rotation of front blade assembly  150  for the prevailing wind speed. Hub  152  further defines a central shaft aperture  154  that is configured to be non-rotatably secured to a drive shaft  128  of electrical generation unit  120 . Front blade assembly  150  further includes a nose cone  158  that is secured to hub  152  to improve the aerodynamic performance of wind turbine assembly  100 . 
     Similarly to front blade assembly  150 , rear blade assembly  160  includes a plurality of blades  161  that extend radially outwardly from its hub  162 . Additionally, each blade  161  is secured to hub  162  by a plurality of fasteners (not shown) that pass through corresponding blade recesses  166 . As with front blade assembly, the pitch of each blade  161  may be altered, as is known in the art, to maximize the speed of rotation of front blade assembly  160  for the prevailing wind speed. Hub  162  further includes an axially extending annular wall  164  that is non-rotatably fixed to a body  122  of electrical generation unit  120 . As such, in the preferred embodiment shown, rear blade assembly  160  is non-rotatably fixed to the magnetic portion, or field magnet  124 , of electrical generation unit  120 , whereas front blade assembly  150  is non-rotatably fixed to the windings, or armature  126 , of electrical generation unit  120 , as best seen in  FIG. 6A . In short, armature  126  of electrical generation unit  120  is rotatably supported within body  122 , which defines field magnet  124  of generation unit. Alternately, as shown in  FIG. 6B , field magnet  124  may be non-rotatably fixed to front blade assembly  150  and rotatably supported within armature  126 , which is defined by body  122  of the electrical generation unit  120 . In both instances, radial bearings  125  are provided to rotatably support either field magnet  124  or armature  126  within the other of the electrical components. 
     As best seen in  FIGS. 4 and 5 , a radial bearing assembly  130  is provided to rotatably support electrical generation unit  120  within housing  110  of wind turbine assembly  100 . Radial bearing assembly  130  includes an outer race  132 , an inner race  134  and a plurality of either ball bearings or needle bearings  136  disposed therebetween. Outer race  132  is non-rotatably secured to an inner surface  112  of the wind turbine housing  110 , whereas body  122  of electrical generation unit  120  is non-rotatably secured to an inner surface  135  of inner race  134  of the radial bearing assembly  130 . As such, the entire electrical generation unit  120  is rotatably disposed within housing  110  of wind turbine assembly  100 . Moreover, front blade assembly  150  and rear blade assembly  160  are rotatable with respect to each other, as well as housing  110  of wind turbine assembly  100 . As such, because front blade assembly  150  and rear blade assembly  160  counter-rotate with respect to each other, the revolutions per minute (RPM) of field magnet  124  with respect to armature  126  is effectively doubled as compared to a traditional wind turbine in which one of the armature or the field magnet is non-rotatable with respect to the housing of the wind turbine. Moreover, by providing increased RPM between the armature and the field magnet as compared to traditional wind turbines for the same wind speeds, the sizes of blades  151  and  161  may be reduced as compared to the blades of known wind turbines. Reduced size leads to reduced mass which, in turn, leads to lower cut-in wind speeds for wind turbine  100  as compared to traditional wind turbines. 
     As best seen in  FIG. 2 , the pitch of blades  151  of front blade assembly  150  is selected so that front blade assembly  150  rotates in the counter-clockwise (CCW) direction, whereas the pitch of blades  161  of rear blade assembly  160  is selected such that rear blade assembly  160  rotates in the clockwise (CW) direction. Note, however, in an alternate embodiment, front blade assembly  150  may be selected to rotate in the CW direction whereas rear blade assembly  160  is selected to rotate in the CCW direction. As best seen in  FIGS. 6A and 6B , a slip ring  170  including wire leads  172  is utilized to remove electrical power from armature  126  regardless of whether armature  126  is driven by front blade assembly  150  ( FIG. 6A ) or rear blade assembly  160  ( FIG. 6B ). 
     While one or more preferred embodiments of the invention are described above, it should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit thereof. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.