Abstract:
A wind turbine has a housing with an airflow inlet and an airflow outlet. Enclosed within the housing is a rotor unit having a horizontally oriented shaft and elongated double-sided blades. Each blade has two concave outer surfaces for creating optimum lift regardless of wind flow direction. Secured within the housing and over and under the blades are shroud members which assist in creating a Venturi effect, that is rapid air flow within the housing, further increasing the efficiency of the wind turbine. Louvers are provided on the sides of the housing to optimally direct air flow into, through, and out of the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    A variety of wind driven turbine designs have been proposed and some have been manufactured and put into use. The earliest wind turbines were drag type designs or ones where the turbine blades were pushed by the wind, but created resistance when advanced into the wind. The rotors of such designs rotated slowly and the respective blades slowed the rotor as it advanced into the wind. 
         [0002]    More recently, wind turbine designs are configured to utilize lift instead of drag. While there are many such wind turbine designs, most commercial wind turbines are three blade horizontal axis turbines. The trend is towards larger turbines capable of producing megawatts of electrical power. However, these turbines are expensive and require sophisticated engineering and power distribution systems. 
         [0003]    Traditional wind powered turbine systems, while they do not rely on fossil fuels, still carry with them a number of significant disadvantages including the high initial capital cost and continuing maintenance expenses, especially of large wind turbines. Additional expense is incurred in the need to install electrical transmission lines from the source of wind generation to the location of power use. Running electrical lines also entails obtaining consent and permits from the local municipalities concerned with resource management. Moreover, large turbines can adversely effect the visual amenity of landscapes. Many towns and cities with strict zoning restrictions forbid horizontal wind turbines since they are viewed as eyesores. 
         [0004]    Other disadvantages of existing horizontal wind turbines include their being considered hazards when turbine blades fling ice in bad weather. Sunlight shining on rotating blades also sometimes creates an effect such as flicker vertigo, which can cause an adverse psychological reaction on people and livestock. 
         [0005]    Notwithstanding the above problems and disadvantages of existing wind turbines, the main focus for reducing reliance on fossil fuels using wind energy has been in the creation of wind farms. These wind farms normally have a number of large turbines on vertical towers, rotating about a horizontal axis to supply electricity to users when the rotor blades are turned towards the prevailing wind. Various designs for vertical axis turbines have also been proposed. These turbines have vertically oriented elongated blades rotating about a vertical axis. Nonetheless, the wind turbines in these systems are also subject to the various problems and disadvantages previously described. 
       SUMMARY OF THE INVENTION 
       [0006]    It is thus the object of the present invention to overcome the disadvantages and limitations of existing wind turbines. 
         [0007]    It is thus an object of the present invention to provide a wind turbine which is simple and quiet in operation having relatively few moving parts. 
         [0008]    It is another object of the present invention to provide a wind turbine capable of operating over a wide range of wind speeds and wind directions. 
         [0009]    It is a further object of the present invention to provide a wind turbine which is economical in generating electrical power. 
         [0010]    It is still another object of the present invention to provide a wind turbine which may be used for generating electricity for small and large facilities. 
         [0011]    It is a further object of the present invention to provide a wind turbine which is easily mounted for use in residential locations. 
         [0012]    It is still another object of the present invention to provide a wind turbine which consists of a modular design allowing for the use of individual units to be mounted end to end. 
         [0013]    It is another object of the present invention to provide a wind turbine which uses prevailing ambient wind flow in a most efficient manner, to optimize blade lift and minimize drag. 
         [0014]    These and other objects are accomplished by the present invention, a wind turbine comprising a housing having an airflow inlet and an airflow outlet. Enclosed within the housing is a rotor unit having a horizontally oriented shaft and elongated double-sided blades. Each blade has two concave outer surfaces for creating optimum lift regardless of wind flow direction. Secured within the housing and over and under the blades are shroud members which assist in creating Venturi effect, that is rapid air flow within the housing, further increasing the efficiency of the wind turbine. Louvers are provided on the sides of the housing to optimally direct air flow into, through, and out of the housing. 
         [0015]    The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention, itself, however, both as to its design, construction and use, together with additional features and advantages thereof, are best understood upon review of the following detailed description with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is an isometric view of the wind turbine of the present invention showing its housing and internal components. 
           [0017]      FIG. 2  is a cross-sectional view of the wind turbine of the present invention. 
           [0018]      FIG. 3  is an isometric view of the wind turbine of the present invention with the addition of louvers, vertical fins and housing support roof bracket. 
           [0019]      FIG. 4  is a side view of the blade and shaft arrangement of the wind turbine of the present invention. 
           [0020]      FIG. 5  is an end view of a representative turbine blade of the present invention. 
           [0021]      FIGS. 6   a  and  6   b  are power diagrams depicting the operation of the wind turbine of the present invention. 
           [0022]      FIG. 7  is an isometric view of the wind turbine of the present invention mounted on the roof of a residential structure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Wind turbine  1  of the present invention comprises housing  2  with top shroud  4 , bottom shroud  5 , and end sections  6  and  7 . Air flow inlet  8  and outlet  9  are located at the front and rear sides of housing  2 . Air flow inlet  8  becomes the outlet, and air flow outlet  9  becomes the inlet, depending on wind direction. (See  FIGS. 6   a  and  6   b ). Front and rear sides of housing  2  also comprise horizontally extending louver sets  11  and  13 , each set comprising a plurality of louvers. The louvers are angularly adjustable, as will be discussed in additional detail hereinafter. 
         [0024]    Enclosed within housing  2  is rotor unit  10  comprising horizontally oriented rotor shaft  12  having horizontal axis  14 . Horizontally oriented elongated blades  16 ,  18 ,  20  and  22  are connected to shaft  12  via connecting rods  17 ,  19 ,  21 , and  23 , such that elongated gaps or spaces are left between each of the blades and the shaft. See, for example,  24  in  FIG. 4 , with regard to blade  22  and shaft  12 . These spaces prevent the blockage of air which can inhibit rotation of rotor unit  10  at low wind speeds. 
         [0025]      FIG. 5  shows a representative turbine blade. Turbine blade  16  comprises double-sided concave surfaces  32  and  34 , interior edge  33  and outer edge  35 . Blade tip end plate  40  extends down from the end of outer edge  35  to prevent air flow at the end of blade  16  from spilling over. Each blade in rotor unit  10  is thus configured to be productively utilized when rotated both in the clockwise and counterclockwise directions. 
         [0026]    Rotor unit  10  is supported within housing  2  at one end by a connection between shaft  12  and bearing  42  secured to side section  7 . The other end of shaft  12  is connected to electrical generator, pump or other electrical motive device  44  via a suitable transmission. Rotor unit  10  will rotate in both the clockwise and counterclockwise, depending on wind direction. 
         [0027]    Upper shroud  4  and lower shroud  5  are curved in configuration and are secured to side sections  6  and  7  of housing  2 . As best seen in  FIGS. 1 ,  3 ,  6   a  and  6   b , upper shroud  4  partially encircles the interior, upper region of housing  2  and is positioned such that an elongated open area  50  is created between the blades of rotor unit  10  and the upper shroud when these blades are below the upper shroud. Lower shroud  5  partially encircles the interior, lower region of housing  2  and is positioned such that an elongated open area  52  is created between the blades of rotor unit  10  and the lower shroud when these blades are above the lower shroud. 
         [0028]    The operation of the wind turbine of the present invention is described by reference to  FIGS. 6   a  and  6   b . Wind flow  60  is directed through louver set  11  and inlet  8  at the front side of housing  2  towards rotor unit  10 . The rotor unit has a windward power quarter W, wherein its blades are predominantly driven by lift forces; a drag power quarter D, wherein blades are predominantly pushed by the incident wind flow; a leeward power quarter L, wherein blades are again predominantly driven by lift forces; and a non-power quarter N, wherein blades predominantly produce drag. Air flow exits housing  2  through outlet  9  and louver set  13 . 
         [0029]    Significantly, additional upwards lift is created by the flow in open area  50  between upper shroud  4  and the outer edges of the blades, e.g. outer edges  35  of blade  16 , and outer edge  39  of blade  18 . This additional lift is seen, albeit to a lesser extent, between the outer edges of the blades and lower shroud  5 , in open area  52 . Airflow through open areas  50  and  52  creates a Venturi effect in these locations which materially enhances power generation and reduces drag within housing  2 . It can be appreciated that when wind flow  62  comes from the opposite direction, rotor unit  10  will rotate in a counterclockwise direction, but will experience the same power, drag power, leeward power and non-power quarters, and the enhanced power generation of the Venturi effect between blades and upper and lower shrouds. 
         [0030]    Louver sets  11  and  13  are provided to shield blades from direct air flow and redirect the flow at optimal angles into the retreating blades of rotor unit  10  and towards upper shroud  4  and lower shroud  5 . The louver sets also concentrate air flow towards the blades which rotate away from the louver sets to assist in maintaining non-turbulent air flow. Trailing louver sets, that is those which receive the discharged air flow from rotor unit  10 , also contribute to maintaining a non-turbulent flow of existing air from housing  2 . Louver sets  11  and  13  are pivotable, typically between a range of approximately 30° to 60° relative to incident air flow. This allows incident air flow to be optimally directed as wind speed changes. 
         [0031]    The optimal angle of each louver in louver sets  11  and  13  will be different from its neighboring louver. Each will have a progressively more horizontal angle, such that the bottommost louver starts at about 45° and progresses to the top louver which is almost 0° degrees to the horizontal. All louvers of louver sets  11  and  13  are designed to rotate to the same profile as upper shroud  4  and lower shroud  5 , so they can effectively form a part of the front and rear sides of housing  2 , and thus provide protection from bad weather and the inner components of wind turbine  1 . 
         [0032]    Control of louver sets  11  and  13  may be either by electronic or mechanical means. Electronic sensors may sense the direction and speed of the incident air flow and supply this information to a controller, which regulates the angle of the louvers via electromechanical means. Alternatively, an air flow surface may be connected to the louvers via a suitable mechanical linkage to control their angle. 
         [0033]    As previously described, rotor unit  10  is connected to a generator or other motive device  44 . Generators having a high number of poles may be directly driven to simplify the design and reduce frictional losses. Generators employing permanent magnetic rotors or stators are particularly suitable. Where wind turbine  1  drives an electrical generator, such a unit may be connected to the local electrical supply network so that local generation may be injected into the grid when surplus power is generated. Alternatively, the generator may be connected to an optional power supply. 
         [0034]    Vertically oriented fins  70  are optionally included, as shown in  FIG. 3 , to reduce turbulence and improve utilization of the incident air flow through housing  2 . Housing support roof brackets  72  and  74  are provided to mount housing  2  to a roof or other high surface. 
         [0035]    Housing  2  itself can readily be mounted to roof  100  of a building, house or like structure, as shown in  FIG. 7 . Several housings  2   a ,  2   b , and  2   c  can be aligned in tandem on a roof surface for optimal wind power generation. Housing  2  can also be mounted in a vertical orientation on a stationary building or structure or configured for use on a spar or mast of a sailboat to provide power to the vessel. 
         [0036]    The wind turbine of the present invention is a hybrid utilizing both drag and lift techniques. The wind turbine unit is provided in a compact, simple, and environmentally acceptable housing. It is thus able to be used in locations where wind generation would not otherwise be feasible due to regulatory requirements and other restrictions. The design has few moving parts, and its rotor unit design and its blades do not have to be produced in exacting standards or by use of expensive materials. Housing  2  protects the rotor unit  10  from weathering and ensures that it is safely contained and protected against inadvertent damage by humans, damage caused by animals or birds, and weather. Housing  2  also mitigates visual and noise problems associated with moving components. 
         [0037]    Although four blades are shown in wind turbine  1 , advantageous results can be achieved by use of between three and eight blades. The blades themselves may be formed from a wide variety of materials and processes, including extrusion and molding from metal, plastics, composites (e.g. fiberglass, carbon fiber) etc. The blades curl so it can be arranged to spiral along the length of the rotor unit to provide improved balance. 
         [0038]    Certain novel features and components of this invention are disclosed in detail in order to make the invention clear in at least one form thereof. However, it is to be clearly understood that the invention as disclosed is not necessarily limited to the exact form and details as disclosed, since it is apparent that various modifications and changes may be made without departing from the spirit of the invention.