Patent Publication Number: US-2012043449-A1

Title: Clamp assembly

Description:
FIELD OF THE INVENTION 
     The field of the invention relates to clamps for mounting rods or other load-bearing structures substantially perpendicularly to a shaft. 
     BACKGROUND 
     Wind is an increasing source of energy for driving wind turbines, windmills, and the like, for the production of electrical power. Traditionally, horizontal axis wind turbines were used to power electric generators. However, these horizontal axis wind turbines have several drawbacks. For example, the wind direction may impact the ability of a horizontal axis wind turbines to operate efficiently as the horizontal axis wind turbines must be rotated to face the wind, the large-scale arc of rotation poses a safety threat to aircraft and birds, large-scale horizontal axis wind turbines create a substantial amount of noise due to the speed of rotation at the tips of the blades, and the large-scale size is impractical for single home or other small-scale applications. 
     In recent years, there has been a transition toward vertical axis wind turbines. The design of the wind turbine blades for these vertical axis wind turbines allow the wind turbines to rotate regardless of the wind direction, thus addressing one of the more substantial drawbacks of horizontal axis wind turbines. The vertical axis wind turbine design has a quieter operation because the speed of rotation at the outermost diameter does not reach the speed experienced with the large-scale horizontal axis wind turbines. 
     In some cases, the vertical axis wind turbine employs two wind turbine blades that twist along the length of the vertical shaft of the wind turbine in a configuration that may be referred to as a “helical shape.” The helical shape results in maintaining some part of the wind turbine blade facing the wind regardless of the wind direction. This wind turbine blade configuration requires that the wind turbine blade be connected at various heights along the vertical shaft of the wind turbine and at various positions around the perimeter of the vertical shaft. To secure the wind turbine blade at the various positions and heights, a shaft design and clamp assembly design is needed that will prevent the wind turbine blade from rotating axially or translating vertically along the shaft. Moreover, the needed clamp designs must be inexpensive to manufacture, simple to mount at desired orientations along the length of the shaft, and strong enough to support the variable loads and forces of the wind turbine blades. 
     SUMMARY 
     Embodiments of the invention provide a clamp assembly comprising two substantially identical mechanically coupled brackets. Each bracket may include an elongated end, a curved section adjacent the elongated end, a channel formed by the curved section, and a mating surface adjacent the channel. When the mating surfaces of each bracket are in mating contact with each other, the channels of each bracket are substantially aligned with each other to form a shaft aperture. 
     In some embodiments, the mating surface includes a tongue and a groove, wherein the tongue of the first bracket is coupled to the groove of the second bracket, and wherein the tongue of the second bracket is coupled to the groove of the first bracket. In other embodiments, each bracket comprises at least two connection points that are substantially aligned with each other when the two brackets are coupled. At least two fasteners may be coupled to the at least two aligned connection points. 
     In some embodiments, each bracket further comprises a coupling area, wherein the coupling area is configured to engage a mechanical fastener. Similarly, the elongated end of each bracket may be configured to engage a mechanical fastener. In these embodiments, the coupling area may be coupled to a wind turbine blade, and the elongated end may be coupled to a rod. 
     In some embodiments, the shaft aperture has a shape that is configured to couple the clamp assembly to a shaft having a cross-sectional shape that is substantially similar to the shaft aperture cross-sectional shape. The shape of the shaft aperture and the cross-sectional shape of the shaft may be a rounded rectangle, so that the mounted clamp assembly will not rotate around the shaft when rotational force is applied thereto. In some embodiments, the clamp assembly mounts to a shaft comprising a plurality of notched segments, wherein each notched segment has a cross-sectional shape that is substantially similar to the shaft aperture cross-sectional shape. The plurality of notched segments may be rotated angularly relative to each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a side view of a bracket according to certain exemplary embodiments of the present invention. 
         FIG. 1B  is a side view of the bracket of  FIG. 1A  coupled to another bracket to form a clamp assembly. 
         FIG. 2A  is a side view of the bracket of  FIG. 1A  showing the locations of exemplary connection points. 
         FIG. 2B  is a side view of the clamp assembly of  FIG. 1B  showing the locations of exemplary connection points. 
         FIG. 3A  is a side view of the bracket of  FIG. 1A  showing the locations of additional exemplary connection points. 
         FIG. 3B  is a side view of the clamp assembly of  FIG. 1B  showing the locations of additional exemplary connection points. 
         FIG. 4  is a side view of the clamp assembly of  FIG. 1B  showing a plurality of rods coupled to several of the exemplary connection points. 
         FIG. 5  is an exploded perspective view of the clamp assembly of  FIG. 1B . 
         FIG. 6  is a perspective view of the clamp assembly of  FIG. 1B . 
         FIG. 7  is a perspective view of the clamp assembly of  FIG. 1B  mounted to a shaft. 
         FIG. 8  is a perspective view of a shaft according to one embodiment of the present invention. 
         FIG. 9  is a top view of the shaft of  FIG. 8  coupled to a plurality of clamp assemblies of  FIG. 1B . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention provide a clamp assembly for mounting rods or other load-bearing structures substantially perpendicularly to a shaft, such as a rotor shaft or an axle. For example, a clamp assembly of the present invention may be used for mounting rods to the rotor shaft of a wind turbine, where the rods are substantially perpendicular to the rotor shaft and are used to support the blades of the wind turbine. However, the inventive clamp assemblies described herein are by no means limited for use in the construction of wind turbines. Other suitable applications will be apparent to those of skill in the art after reading the following description of the exemplary embodiments. 
     Exemplary embodiments of the present invention will hereinafter be described with reference to the drawings, in which like numerals are used to indicate like elements. For the sake of convenience, the drawings are not drawn to scale or with precise perspective and any reference herein to exemplary dimensions of the inventive clamp assembly or elements thereof are not intended to be reflected as such in the drawings. In addition, directional references used herein, such as front, back, top, bottom, etc. are intended to be relative to ordinary or normal usage of the described clamp assembly and are therefore not to be taken as limiting of the present invention in cases where clamp assembly is used in other manners. 
       FIGS. 1A-7  illustrate certain exemplary embodiments of a clamp assembly  10  and its constituent brackets  12 . As shown, the clamp assembly  10  comprises two brackets  12  coupled to one another. Each bracket  12  may be formed from a solid piece of iron, mild steel, aluminum, stainless steel, alloy steel, copper, brass, titanium, other metallic materials, composite materials, carbon fiber, plastics, fiberglass, or other similar materials. For example, the brackets  12  may be cut from a solid piece of material using techniques such as laser cutting, plasma cutting, waterjet cutting, milling, wire cutting, and other similar cutting processes. In some embodiments, the brackets  12  may be hardened and/or tensioned to provide additional strength. In other embodiments, for example where superior material strength is not a primary concern, the brackets  12  may be formed using die casting, molding or other suitable techniques. 
     As shown in  FIG. 1A , an exemplary bracket  12  comprises an elongated end  16 , a curved section  18 , a groove  20 , an angled coupling area  22 , and a tongue  24 . The shape of the bracket  12  is configured to couple with a second bracket  12  having a substantially identical or at least similar shape, thereby forming the clamp assembly  10  as shown in  FIG. 1B . In the illustrated embodiments, each bracket  12  has a mating surface  26  that is configured to engage with a corresponding mating surface  26  of the second bracket  12 . The mating surface  26  is defined as the portion of the surface of a bracket  12  that is placed in contact with an adjacent bracket  12  when the two brackets  12  are coupled to one another. 
     As also shown in  FIG. 1B , the two brackets  12  can be engaged via a “tongue and groove” arrangement, where the tongue  24  of the first bracket  12  is inserted into the groove  20  of the second bracket  12 , and the tongue  24  of the second bracket  12  is inserted into the groove  20  of the first bracket  12 . One of skill in the relevant art will understand that the tongue and groove design may provide additional strength to the clamp assembly  10 , which can be of particular importance in applications where the clamp assembly  10  will bear heavy loads and/or be subject to strong shears and other forces. However, the tongue and groove feature of the inventive clamp assembly  10  is considered to be an optional feature, which may not be required in all embodiments. In the illustrated embodiments, the tongue  24  of each bracket  12  is a wedge-shaped projection that corresponds to the wedge shape of the groove  20 . However, one of skill in the relevant art will understand that many other suitable shapes and arrangement for achieving such a tongue and groove (or interlocking) effect between the brackets  12  are possible. 
     For purposes of symmetry and ease of manufacturing, the two brackets  12  of the clamp assembly  10  may have substantially identical or at least substantially similar overall shapes, as shown throughout the figures. In certain alternative embodiments, however, the two brackets  12  may have similarly-shaped mating surfaces  26 , but differently-shaped non-mating surfaces  36 , where the non-mating surface  36  is defined as the portion of the surface of the bracket  12  that is not placed in contact with the adjacent bracket  12  when the two brackets  12  are coupled to one another. 
     In certain exemplary embodiments, the two brackets  12  of the clamp assembly  10  may be secured to one another via mechanical fasteners, such as screws, bolts, pins, etc. For example, as shown in  FIGS. 2A-2B , each bracket  12  may include connection points  28  and  30 . These exemplary connection points  28  and  30  are positioned on each bracket  12  so as to achieve paired alignment when the two brackets  12  are coupled. In some embodiments, the connection points  28  and  30  are holes formed in the bracket  12 . As shown, the hole of connection point  28  may extend completely through the bracket and the hole of connection point may  30  extends partially through the bracket  12 . Both holes of connections points  28  and  30  may be tapped to form threads for accepting a screw or bolt. Alternatively, only the hole of connection point  30  may be tapped and the hole of connection point  28  may be shaped to receive the top of a bolt. In other embodiments, the connection points  28  and  30  may be bored holes that allow a bolt to pass through the coupled brackets  12 , where the bolt is secured with a nut or a check-nut. Those skilled in the art will appreciate that other types of mechanical connection points  28  and  30  are also possible. 
     As shown in  FIGS. 3A-3B , each bracket  12  may include one or more additional connection points  32  and  46 . For example, connection point  32  may be a tapped hole formed in the elongated end  16  of the bracket and connection point  46  may be a tapped hole formed in the angled coupling area  22 , each for accepting a screw, bolt, threaded projection, or other mechanical fastener. Connection points  32  may be used for coupling rods  34  or other load-bearing structures to the clamp assembly  10 , as shown in  FIG. 4 . By way of example, the rods  34  may be used to support wind turbine blades (not shown). The rods  34  may be made from steel, aluminum, plastic, fiber glass, or any other material of suitable strength for the intended application. Each rod  34  may have a threaded end that screws into the tapped hole of the applicable connection point  32 . Other mechanical connections between the rods  34  and the brackets  12  are possible. In certain embodiments, the strength of the clamp assembly  10  allows it to bear substantial load and shear or rotational forces. Thus, the clamp assembly  10  may be capable of supporting rods  34  having lengths up to 48 inches or longer, depending of course on the construction and material of the rods  34  and the application of the clamp assembly  10 . In some embodiments, the rods  34  can be of variable length. 
     Optional connection points  46  may be included at the angled coupling area  22  positioned adjacent the tongue  24  and the curved section  18 . These connection points  46  may be used for coupling objects or structures, such as portions of wind turbine blades or supports therefor (not shown) to the clamp assembly  10  at certain fixed angles, which angles are dictated by the configuration of the angled coupling area  22 . One of skill in the relevant art will understand that the angled coupling area  22  may have configurations different from those shown in the figures. In some embodiments, as better illustrated in  FIGS. 5-7 , the elongated end  16  of each bracket  12  has a rectilinear cross-section. However, one of skill in the relevant art will understand that the elongated end  16  may have many other suitable cross-sectional shapes, including but not limited to circular, parabolic, I-shaped, T-shape, D-shape, U-shape, triangular, pentagonal, hexagonal, octagonal, or other similar shape. 
     In the embodiment illustrated in  FIGS. 1-7 , and as noted with reference numerals in  FIGS. 3A-3B , the curved section  18  of each bracket  12  includes a curved exterior wall  38  and a curved interior wall  40 . Each end of the curved interior wall  40  terminates with a substantially straight portion  42 . As a result, the curved section  18  forms a substantially “U shaped” channel  44  surrounded by the mating surface  26  of the bracket  12 . As shown, the curved section  18  of one bracket  12  may be substantially aligned with the curved section  18  of a second bracket  12 , such that the respective channels  44  form an aperture  14  through the clamp assembly  10 . In the illustrated embodiments, the aperture  14  has a rounded-rectangle shape where two sides are curved and two sides are straight. One of skill in the relevant art will understand that the aperture  14  may have many other suitable shapes, including but not limited to circular, parabolic, rectilinear, hexagonal, octagonal, or other similar shape. 
     As shown in  FIG. 7 , the clamp assembly  10  may be mounted to a shaft  50  that fits through the aperture  14 . The shaft  50  preferably has a cross-sectional shape that is the same or substantially the same as that of the aperture  14 . Thus, in embodiments where the aperture  14  of the clamp assembly  10  has a rounded-rectangle shape, the cross-sectional shape of the shaft  50  is also a rounded rectangle. In such embodiments, the rounded-rectangular shape of the aperture  14  and the shaft  50  prevents the clamp assembly  10  from spinning around the shaft  50  when a rotational force is applied to the clamp assembly  10 . One of skill in the relevant art will understand that any appropriate cross-sectional shape that similarly couples the clamp assembly  10  to the shaft  50  while preventing the clamp assembly  10  from rotating around the shaft  50  may be used. In other embodiments, it may be desirable to have an aperture  14  with a cross-sectional shape that does allow the clamp assembly  10  to rotate around the shaft  50 . As should be apparent, the curved section  18  of each bracket  12  may be sized and shaped so that the resulting aperture  14  fits tightly around the shaft  50 . Accordingly, the two brackets  12  may be fitted around the shaft  50  and mechanically coupled together via connection points  28  and  30 , and optionally engaged via the tongue and groove arrangement or other interlocking effect, thus mounting the clamp assembly  10  to the shaft  50   
     As shown in  FIG. 8 , the shaft  50  may have an overall circular cross-sectional shape. One of skill in the relevant art will understand that the shaft  50  may have many other suitable shapes, including but not limited to parabolic, rectilinear, hexagonal, octagonal, or other similar shape. In this embodiment, the shaft  50  may include at least one notched segment  52 . As a result, the shaft  50 , in the notched segment  52  location, has a cross-sectional shape that is the same or substantially the same as that of the aperture  14 . In such embodiments, the rounded-rectangular shape of the aperture  14  and the similarly-shaped notched segment  52  of the shaft  50  prevents the clamp assembly  10  from spinning around the shaft  50  when a rotational force is applied to the clamp assembly  10 . 
     As is shown in  FIG. 8 , the notched segment  52  may optionally include a half-segment  521  with a height that is the same or substantially the same as that of the thickness of the bracket  12 . The opposing half-segment  522  that joins with the half-segment  521  has a height that is approximately twice that of the thickness of the bracket  12 . This configuration allows an untrained installer to couple the clamp assembly  10  to the shaft  50  in a precise location and orientation without the need for technical expertise. Specifically, the first bracket  12  is coupled to the half-segment  521 . The overall shape of the half-segment  521  is the same or substantially the same shape as the channel  44  and the thickness of the bracket  12  so that the first bracket  12  cannot move up/down or side-to-side when coupled to the half-segment  521 . The double-sized height of the half-segment  522  allows the second bracket  12  to couple to the half-segment  522  above the location of the first bracket  12 . Likewise, the overall shape of the half-segment  522  is the same or substantially the same shape as the channel  44  so that the second bracket  12  cannot move side-to-side when coupled to the half-segment  522 , but can slide down the half-segment  522  to couple to the first bracket  12  in a tongue and groove arrangement. 
     In the embodiment shown in  FIG. 8 , the shaft  50  may include a plurality of notched segments  52   a - f , each of which has a substantially identical cross-sectional shape. The segments  52   a - f  are positioned along the shaft  50 , but each notched segment  52   a - f  is rotated a fixed amount relative to the adjacent notched segments. For example, in the illustrated embodiment, a second notched segment  52   b  is rotated approximately 36 degrees relative to a first notched segment  52   a . Likewise, a third notched segment  52   c  is rotated approximately 36 degrees relative to the second notched segment  52   b , so that the third notched segment  52   c  is rotated a total of 72 degrees from the first notched segment  52   a . The fourth notched segment  52   d  is rotated approximately 36 degrees relative to the third notched segment  52   c , so that the fourth notched segment  52   d  is rotated approximately 108 degrees relative to the first notched segment  52   a . The fifth notched segment  52   e  is rotated approximately 36 degrees relative to the fourth notched segment  52   d , so that the fifth notched segment  52  is rotated approximately 144 degrees relative to the first notched segment  52   a . Finally, the sixth notched segment  52   f  is rotated approximately 36 degrees relative to the fifth notched segment  52   e , so that the sixth notched segment  52   f  is rotated approximately 180 degrees relative to the first notched segment  52   a . Thus, the sixth notched segment  52   f  and the first notched segment  52   a  are in alignment, but 180 degrees out of phase, relative to each other. 
     In this embodiment, the shaft  50  comprises a plurality of notched segments  52   a - f  in a rotating pattern so that a plurality of clamp assemblies  10  may be readily affixed to the shaft  50  in predetermined angles and positions along the length of the shaft  50 . When a clamp assembly  10  has been mounted to each notched segment  52   a - f , rods  34  may be coupled to each elongated end  16  thereof, as shown in  FIG. 9 . In this configuration, a pair of helical-shaped wind turbine blades (not shown) may be supported by the rods  34  (and, optionally, the angled coupling areas  22  of the clamp assembly  10 ). The heights and angular configurations of the rods  34 , relative to one another, may be spaced to conform to the twisting shape of the helical wind turbine blades. In some embodiments, rods  34  can be of different lengths, which will change the shape and profile of the helical wind turbine blades. The shape of the wind turbine blades may be adjusted by, for example, changing the length of the rods  34  and/or by changing the shaft  50  to include a different rotation pattern of the notched segments  52   a - f  or different spacing of the notched segments  52   a - f  along the length of the shaft  50 . 
     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Further modifications and adaptations to these embodiments will be apparent to those skilled in the art. The features and aspects of the present invention have been described or depicted by way of example only and are therefore not intended to be interpreted as required or essential elements of the invention unless otherwise so stated. It should be understood, therefore, that the foregoing relates only to certain exemplary embodiments of the invention, and that numerous changes and additions may be made thereto without departing from the spirit and scope of the invention as defined by any appended claims.