Abstract:
A collapsible vertical-axis turbine for wind or hydro applications is provided, comprising a plurality of vertical blades hingedly connected to a plurality of support arms, a tower having a rotating section, the rotating section hingedly connected to the plurality of support arms. In operating mode, the support arms achieve a substantially horizontal position in the operating mode, and in a collapsed mode the plurality of vertical blades preferably nest substantially adjacent and substantially parallel to the tower. A cable means is provided for erecting the vertical blades into an operating mode. The disclosed configuration is easy to erect and collapse for transport, and is well-suited to be implemented as a small to medium scale turbine for deployment to remote locations.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to wind and/or hydro turbine technology. The present invention more particularly relates to vertical-axis turbines. 
       BACKGROUND OF THE INVENTION 
       [0002]    Wind energy remains as one of the most promising renewable energy resources available. It is abundant, inexhaustible, widely distributed and clean. Because of these attributes, there continues to be intensive interest and research in harvesting wind energy. 
         [0003]    In essence, a wind energy system, such as a wind turbine, transforms the kinetic wind energy into electrical or mechanical or energy that can be harnessed for practical use. There are numerous existing wind turbine configurations. Some are hundreds and perhaps even thousands of years old. Old “windmill” technology used wind energy to turn mechanical machinery to carry out physical work, like crushing grain or pumping water. Modern turbine technology operates by converting kinetic energy from the rotation of turbine blades into electrical energy through the use of an electrical generator. 
         [0004]    Wind turbines come in many sizes, shapes and configurations, and have power ratings ranging from 250 watts to 5 megawatts. Generally speaking, two basic turbine design types have emerged: vertical-axis (including “egg-beater” or Darrieus-type, having curved airfoils) and horizontal-axis (propeller). The horizontal-axis wind turbines are the most common, constituting nearly all of the larger scale implementations in the global market. 
         [0005]    Despite being less popular, a vertical-axis turbine arrangement has a number of general advantages over horizontal-axis turbines. These include:
       in a vertical-axis turbine, the generator can be placed at the ground level for easy servicing;   the main supporting tower may be relatively light because of lesser transverse wind forces;   vertical-axis designs do not require specific positioning based on wind direction; and   “Pitching” of the vertical blades, i.e. altering the airfoil blade pitch to improve efficiency, is often not required.       
 
         [0010]    Wind turbines are currently used to generate electricity for various uses, including for homes and communities, businesses, and for sale back to utility grids. Vertical-axis turbines are well-suited for smaller or remote applications to provide electricity where infrastructure is lacking. 
         [0011]    There have been some notable developments in the field of vertical-axis wind turbines. For example, Dery et al. in U.S. Pat. No. 6,979,170 and U.S. Patent Application No. 2004/0120820 describe a self-erecting vertical-axis windmill and method. However, the configuration taught therein is relatively complicated and only provides a means for the tower self-erect, and not the blade structure. 
         [0012]    U.S. Pat. No. 4,624,624 to Yum describes a collapsible vertical wind mill having four wings. However, one of the drawbacks is that the wings are arranged in a rhombic formation, with the result that they create modest wind leverage. Further, the device when collapsed is not compact to facilitate transportation. 
         [0013]    In addition to harvesting wind energy, vertical-axis turbines have been implemented in extracting energy from the sea. Several of these hydro turbine devices have been proposed, for example, the DAVIS™ turbine by Blue Energy Canada Inc., or the KOBOLD™ turbine by Ponte di Archimede S.p.A. However, these devices do not feature collapsibility to allow for easy transport. 
         [0014]    In view of the foregoing, what is needed is a vertical-axis turbine that is easy to erect, collapse and transport. 
       SUMMARY OF THE INVENTION 
       [0015]    In one aspect, the present invention provides a collapsible vertical-axis turbine including a tower having a rotating section, the rotating section hingedly connected to a plurality of support arms, a plurality of vertical blades hingedly connected to the plurality of support arms. In operating mode, the support arms achieve a substantially horizontal position in the operating mode, and in a collapsed mode the plurality of vertical blades preferably nest substantially adjacent and substantially parallel to the tower. 
         [0016]    In another aspect, the present invention provides a cable means for erecting the vertical blades of the collapsible vertical-axis turbine to an operating mode. In one embodiment, the cable means is a cable system including a winch and a pulley, with the winch and the pulley centrally located on the rotating section of the tower. 
         [0017]    The collapsibility of the turbine of the present invention advantageously allows for the turbine to be erected/collapsed for installation, required maintenance, due to high wind conditions, etc. The turbine of the present invention is relatively inexpensive and, because it is easy to erect and collapse, is ideally suited for deployment in remote locations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    A detailed description of an embodiment is provided herein below by way of example only and with reference to the following drawings, in which: 
           [0019]      FIG. 1  illustrates a wind turbine erected in operation mode in accordance with the present invention; 
           [0020]      FIG. 2A  illustrates a collapsed wind turbine; 
           [0021]      FIG. 2B  illustrates a wind turbine in an intermediate configuration; 
           [0022]      FIG. 3A  and  FIG. 3B  are side views of a turbine in operation mode and in an intermediate configuration, respectively, illustrating further detail; 
           [0023]      FIG. 4A  and  FIG. 4B  are a top view and a side view, respectively, of a supporting arm joining the ring with the pin engaged (operation mode); 
           [0024]      FIG. 5A  and  FIG. 5B  are a top view and a side view, respectively, of a supporting arm joining the ring with the pin disengaged (collapsed mode); 
           [0025]      FIG. 6  illustrates a potentional/possible position for the winch; 
           [0026]      FIG. 7  illustrates a potentional/possible position for the lever for use as a secondary system; and 
           [0027]      FIG. 8  is a top view of a turbine. 
       
    
    
       [0028]    In the drawings, one embodiment of the invention is illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The present invention is directed at a collapsible vertical-axis turbine for wind or hydro applications. The configuration disclosed herein allows for the transport, installation, operation and maintenance (including cleaning) of a small to medium turbine, suitable for “remote” locations where some of the infrastructure to meet these activities is lacking, especially since no cranes are required. 
         [0030]    Advantageously, the present invention also allows the turbine to collapse for either transportation or in cases of inclement weather, when necessary, when there are strong winds that could potentially damage the turbine, as in hurricane conditions. The usefulness of this innovation increases with the size of the turbine, with the lower range being a turbine that generates about 250 W of power. 
         [0031]    The present invention is preferably implemented in a wind turbine (as illustrated in the drawings) capable of generating 250 W to 1 MW of electricity, and having a tower height of 2 to 120 m. However, other embodiments are possible, and it should be understood that the present invention includes implementing the turbine underwater as a hydro power generator. 
         [0032]    As discussed above, vertical-axis turbines have many variants. However, to enable easy transport to the site, the present invention provides a vertical-axis turbine having essentially straight blades. There are a number of advantages to having a vertical-axis configuration, including: (i) blades can be straight do not need to be pitched, so they are generally less expensive to make; (ii) the system does not have to move according to wind direction; and (iii) the turbine design as a whole is generally less complicated and therefore less expensive to manufacture. Furthermore, a vertical-axis wind turbine that is collapsible allows for easy transportation, and the collapsibility is advantageous in avoiding storm damage. 
         [0033]    An embodiment of the present invention is shown in  FIG. 1 , which illustrates a collapsible vertical-axis wind turbine  10  erected in an operation mode. The turbine  10  comprises airfoils or blades  12  connected to blade support arms  14 , which are in turn connected to a rotating section or hub  20  supported by a stationary tower  16 , the tower  16  having a base  18 . The hub  20  has an upper ring  22  and a lower ring  23 . The blades  12  are supported by the arms  14  and cables  24 , as discussed below. Preferably and advantageously, the gearbox and generator (not shown) are located at the ground level to allow easy access, e.g., for maintenance. 
         [0034]    In order to keep the overall weight of the system down, it is preferable that the blades  12  are fabricated from a light but strong material. For example, the blades  12  could be fabricated by fibreglass pultrusion. Similarly, the tower  16  could be designed as a lattice structure of either steel or aluminium. 
         [0035]      FIG. 2A  shows the turbine  10  in a collapsed mode, e.g., ready for transport. In this mode, the blades  12  reside advantageously alongside the periphery of the tower  16 , thereby minimizing the transport size of the turbine  10 .  FIG. 2B  shows the same wind turbine in an intermediate configuration. 
         [0036]    The collapsed state allows the turbine  10  (when implemented as a wind turbine) to better withstand strong winds during a storm. In addition, it is possible to have a maintenance platform (not shown) travel up and down along the length of the tower  16 , depending on the height of the tower  16 . 
         [0037]    The tower  16  is shown as having a triangular cross-section, but it should be understood that it can take one of any number of shapes, as would be recognized by one skilled in the art. Further, although the figures depict a turbine  10  having three blades  12 , it should be understood that the present invention contemplates any number of blades, but preferably two to six. Moreover, although the figures illustrate two horizontal support arms  14  located at the top and bottom of the hub  20 , any number of intermediate supports could be included. 
         [0038]      FIG. 3A  and  FIG. 3B  illustrate an embodiment of the present invention in further detail. The turbine  10  includes a cable system, the cable system comprising winches  28 , pulleys  34  and a cable  24 , the cable being attached to the blades  12  at a connection point toward the bottom of the blade  12 . The cable system provides the primary means for erecting and collapsing the support arms  14  and blades  12 . In particular, the winches  28  pull or release the cables  24 , thereby erecting or collapsing the support arms  14  and blades  12 . 
         [0039]    Optionally, a secondary system means for erecting and collapsing the support arms  14  and blades  12  may be provided, the secondary means including a lever  12  positioned in the tower  16 , discussed below. 
         [0040]    As shown in  FIG. 4A  and  FIG. 4B , the support arms  14  are connected to the upper ring  22  via an inner hinge and hinge pin  30  that may be located at or near the end of the support arm  14 . The support arms  14  are connected to the lower ring  23  in the same manner. The support arms  14  are connected to the blades  12  via an outer hinge and hinge pin  32 . 
         [0041]    A locking pin  26  in the top ring  22  is preferably engaged for security when the turbine  10  is in the operating mode. Depending on the loads on and flexibility of the various components of the turbine  10 , the locking pin  26  and its engaging mechanism could be replicated for all upper and lower support arms  14 , as well as on the lower ring  23 . 
         [0042]    As shown in  FIG. 5A  and  FIG. 5B , when the locking pin  26  is disengaged, the support arm  14  is free to rotate about the inner hinge and hinge pin  30 . The blade  12  is free to rotate about the outer hinge and hinge pin  32 . Thus, it should be understood that the configuration composed of arms  14 , blade  12  and hub  20  forms a parallelogram when viewed from the side, and the blades  12  are generally maintained in substantially vertical orientation and preferably parallel to the tower  16 . 
         [0043]    The cable system, comprising winches  28 , pulleys  34  and a cable  24 , controls the angle of the arms  14  in the case of disengagement of the locking pin  26 . A potential/possible position for the winch  28  is shown in  FIG. 6 . 
         [0044]    It should be understood that although this embodiment features a cable system having a winch  28  and a pulley  34 , the present invention is not limited to these particular components but includes variants achieving the same function, as would be recognized by one skilled in the art. 
         [0045]    According to a further aspect of the present invention, depending on the turbine  10  configuration, particularly its weight, and even more particularly the weight of the arms  14  and blades  12 , the cable system can be used for this purpose only until the angle α (shown in  FIG. 3B ) reaches a specific threshold value. At this point, the leverage required by pulling/releasing the cables may be too great for a winch. Therefore, further erecting/collapsing of the rotor can be accomplished by a secondary system. This secondary system, according to an embodiment, comprises a lever  36  that pivots around pivot point  38 , the pivot point  38  located on the tower  16  as illustrated in  FIG. 7 . The lever  36  can be operated either manually or using an automated system simply by attaching a cable or rope to its end, as shown. The geometry of the lever  36  is such that it makes contact with a lower support arm  14  when α reaches the specific value. At that point the position of the lever  36  is in an “open” position. There are several possible extensions to this secondary system. As an example, the lever  36  could be designed such that its natural position is in the “open” position. Further, the addition of a damper to the secondary system will ensure safety in case cable  24  should break. Each of the blades  12  preferably has a lever  36  associated with it. 
         [0046]    To avoid any interference with the tower  16  having a triangular horizontal cross-section, including its lattice work (if any), and to ensure proper interface with the levers  36 , the locking pins  26  are engaged with the upper and lower rings  22 ,  23  such that the locking pins  26  can only disengage when the position of the arms  14  and blades  12  relative to the tower  16  reaches an angle of approximately equal to β as illustrated in  FIG. 8 . β is a predefined value and dependent on specific configuration of the wind turbine  10 . The engagement and disengagement of locking pins  26  can be achieved mechanically as well as electrically, as would be appreciated by a person of skill in the art. This secondary system may be incorporated in the support arm  14  if the hinge pin  30  is located some distance from the inner end of the support arm  14 . 
         [0047]    It will be appreciated by those skilled in the art that other variations of the preferred embodiment may also be practised without departing from the scope of the invention.