Wind energy conversion system

#1. Field of the Invention

#The present invention relates generally to wind energy conversion systems in which kinetic energy of wind is converted into electric power and, more particularly, to wind energy conversion systems having blade assemblies carrying rotor elements for movement past stator elements to produce electric current.

#2. Brief Discussion of the Related Art

#FIG. 1A is a broken side view of a wind energy conversion system according to the present invention.

#FIG. 1B is a side view of the wind energy conversion system.

#FIG. 2 is a broken side view depicting upper and lower wind turbines of the wind energy conversion system.

#A wind energy conversion system or wind power system 10 according to the present invention is illustrated in FIGS. 1A and 1B and comprises upper and lower wind turbines 12a and 12b forming an electrical generator, a tower 14 supporting the wind turbines 12a and 12b at an elevated position above the ground for rotation about a vertical rotation axis 15, an air intake hood or snorkel 16 disposed over the upper wind turbine 12a for directing intake air to the wind turbines, a rudder assembly 18 for positioning the hood 16, and an exhaust plenum 20 disposed beneath the lower wind turbine 12b for exhausting air from the wind turbines. Although the wind energy conversion system 10 is shown as comprising upper and lower wind turbines 12a and 12b, it should be appreciated that the wind energy conversion system may comprise a single wind turbine, such as wind turbine 12a or 12b, forming the electrical generator as disclosed in prior provisional patent application Ser. No. 60/448,355 filed Feb. 20, 2003 and incorporated herein by reference. Each wind turbine 12a and 12b produces an electrical power output directly and independently via rotors carried by blade assemblies of the wind turbines rotating past stators of the wind turbines, respectively. Power output from the wind turbines is supplied to an electrical device 22 which may comprise an electrical load and/or an electrical storage device such as a battery bank comprising one or more batteries.

#Wind turbines 12a and 12b are essentially identical and are best illustrated in FIGS. 2 and 3, it being noted that various components of the wind energy conversion system described and/or illustrated herein have been omitted from FIGS. 1A and 1B for the sake of clarity. FIG. 3 depicts the upper wind turbine 12a but is also applicable to the lower wind turbine 12b. Each wind turbine 12a and 12b comprises a blade assembly including an inner circumferential rim 24 having the rotation axis 15 as its central axis, an outer circumferential rim 25 concentric with the inner rim 24, and a plurality of blades 26 extending between the inner and outer rims radial to the rotation axis 15. The blade assemblies are spaced from one another along the vertical rotation axis 15, with each blade assembly rotating in a horizontal plane perpendicular or essentially perpendicular to the rotation axis 15. The horizontal planes of rotation for the blade assemblies of the upper and lower wind turbines 12a and 12b are therefore in spaced parallel relation. The blade assemblies for the upper and lower wind turbines 12a and 12b are essentially identical to one another, but the blades for the upper wind turbine 12a have a pitch angle oriented in opposition to the pitch angle of the blades of the lower wind turbine 12b such that the blade assemblies for the upper and lower wind turbines are rotated in opposite directions about the rotation axis 15 by air flowing through the blade assemblies. As shown by arrows in FIG. 2, the blade assembly for the upper wind turbine 12a, i.e. the upper blade assembly, rotates counterclockwise about the rotation axis 15 while the blade assembly for the lower wind turbine 12b, i.e. the lower blade assembly, rotates clockwise about the rotation axis 15. The use of counter-rotating wind turbines is advantageous for reducing torque on tower 14. As shown in FIG. 2, which shows fewer blades than FIG. 3, each blade 26 has a cross-sectional configuration of an air foil with a thicker leading edge facing the direction of rotation and a thinner trailing edge. As seen in FIGS. 2 and 3, each blade 26 has a width that tapers from an outer end to an inner end of the blade, and the annular area between the outer and inner rims 24 and 25 of each blade assembly presents spaces 27 alternating with the blades 26. Each blade 26 may be economically constructed as an outer skin or layer of aluminum, fiberglass or molded plastic filled with expandable foam for rigidity.

#Each blade 26 is mounted on a control rod 28 disposed radial to the rotation axis 15. The control rods 28 pass through the blades 26, respectively, and each control rod 28 defines a pitch axis 29, radial to the rotation axis 15, about which the corresponding blade is rotatable to adjust the blade pitch angle as explained further below. The blades 26 for each blade assembly are disposed within the annular area defined between the outer rim 25 and the inner rim 24 of the blade assembly, with the pitch axes 29 at equally spaced radial locations about the rotation axis 15 as best seen in FIG. 3. The number of blades 26 for each blade assembly may vary and, as depicted in FIG. 3, each blade assembly may have ten blades 26 and ten spaces 27 alternating with the blades 26. Preferably, the spaces 27 for each blade assembly account for about 50 percent of the area between the inner rim 24 and the outer rim 25. The inner rim 24 for each blade assembly circumscribes a void as virtually no power is produced at the short radius, low torque position. A control drum 30 is disposed within and fills both voids and is secured to the tower. When only one turbine is employed, the blade assembly may consist of a full compliment of blades without spaces 27.