BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to generation of electrical power utilizing wind and, more particularly, to systems and methods for an increased efficiency wind power generator.

(2) Description of the Prior Art

At a time of both ever-increasing energy needs and non-renewable petroleum products to meet those needs, now is the time to consider the development and implementation of alternate energy sources. Wind generation of electricity is not a newidea; some believe the first wind generator was created by Poul la Cour in 1891 to generate hydrogen for the gaslights in his school. Since that time, a tremendous amount of engineering and development has gone into wind generators.

Bentz' law (formulated by the German Physicist Albert Bentz in 1919) states that you can only convert less than 16/27 (59%) of the kinetic energy of the wind to mechanical energy using a wind turbine. From research done in Denmark, a typicalwind turbine generator runs at about 20% efficiency. This is primarily due to the effects of changing wind speed. For a particular wind turbine generator, calculations are made, based on the average wind speed for that area, to determine the optimumturbine and generator size. The maximum efficiency (typically about 40% to 50%) is reached at a particular wind speed. As the wind speed increases, the efficiency decreases.

Previous efforts to solve problems related to the above are described by the following patents:

U.S. Pat. No. 4,017,205, issued Apr. 12, 1977, to V. W. Bolie, discloses a vertical axis windmill having a horizontal base, preferably circular in configuration, sitting on the earth's surface, a dome having a horizontal bottom spaced abovethe base supported on a plurality of columns to provide an annular space below the dome bottom, a conical baffle positioned on the base below the dome, the conical axis being coincidental with the vertical axis of the dome, the dome having a circularroof orifice therein coaxial with the axis of the conical baffle, a vertical shaft supported coaxially by the conical baffle and an impeller affixed to the shaft and positioned in the dome circular orifice. Wind blowing relative to the windmill causes alifting force by the aerodynamic effect of the dome, the wind passing upwardly through the annular opening and upwardly through the dome orifice, imparting rotational energy to the impeller. Power using apparatus such as generators or the like may beattached to the rotating vertical shaft. An alternate embodiment includes the utilization of a plurality of vertical vanes between the base and the dome, exterior of the conical baffle to more effectively direct the flow of air upwardly through the domeorifice.

U.S. Pat. No. 4,585,950, issued Apr. 29, 1986, to A. M. Lund, discloses multiple induction type generators drivingly connected to an impeller. As wind velocity increases, the generators are successively activated until all of the generatorsare operating at a maximum wind velocity. As the wind velocity decreases, the generators are successively de-activated until all of the generators are inoperative below a minimum wind velocity. Wind energy is more efficiently converted into electricpower where impeller RPM must be maintained substantially constant under varying wind conditions to achieve the desired constant phase of the AC output.

U.S. Pat. No. 5,057,696, issued Oct. 15, 1991, to R. N. Thomas, discloses a vertical windmill employing aerodynamic lift includes stators that form an omnidirectional diffuser and can rotate out of the wind to reduce the destructive tendenciesin high winds. A braking mechanism included in the windmill uses rotation of the airfoils to reduce the lift caused by the wind and disengagement of the airfoils to reduce nearly all lift on the airfoils. Centrifugal force is used to activate the brakein high winds, both to slow the rotor speed and, in extreme winds, to stop the rotor. A motor is provided to drive the windmill to simplify controls and increase energy production.

U.S. Pat. No. 5,518,362, issued May 21, 1996, to A. E. Kivilammi, discloses a method and wind power station for the utilization wind energy and transformation of wind energy into electrical energy. The wind power station comprises severalrotors rotating by wind energy and connected to electricity producing generators. From these rotors the wind stream is directed also to a separate, main rotor to thereby maximize the output from a given stream.

U.S. Pat. No. 6,242,818, issued Jun. 5, 2001, to R. H. Smedley, discloses a vertical axis wind turbine having a plurality of blades around its periphery and a pivotable door associated with each blade. Each door has a pivot axis that isinclined outwardly toward the bottom of the turbine so that gravitational forces will pull the doors toward an open position. The doors are designed to move toward a closed position to at least partially block wind forces from the blades when the rotorrotates at potentially damaging speeds. The turbine has mating coils on the rotor and the support column to generate electrical energy when the rotor rotates.

U.S. Pat. No. 6,249,059, issued Jun. 19, 2001, to N. Hosoda, discloses a wind power device comprising a wind guide and a twisted member in the wind guide. The wind guide is rotatable around a vertical shaft so that a front opening of the windguide may always face the wind. The wind which comes into the wind guide is guided around the twisted member and reaches to a blade wheel, which actuates a generator via gears to create electric power.

U.S. Pat. No. 6,448,669, issued Sep. 10, 2002, to D. M. Elder, discloses a turbine used to convert wind or fluid energy, and in some embodiments the kinetic energy of water, into mechanical energy, more specifically, a long axis type ofvertical-axis turbine allowing large columns of air or water to be harnessed. These devices differ from horizontal-axis (propeller) type windmills or watermills which typically rotate about a vertical axis in order that they may face directly into awind. The present invention is designed to be employed as a cost effective alternate power source in any wind or water current condition from a breeze to a gale wind, to a slow to moderate to fast water currents. To increase the structural integrity,the torque generating elements, namely, the rotor blades, are not directly attached to the shaft but rather, they attach to the round top and bottom rotor cage plates through which torque forces generated can be transferred to the shaft. The uniquedesign of an open cover on the top of the wind or water turbine allows wind or water from the direction above the turbine to be harnessed. The top shield structure has created a calm wind or water area between the shield and the top of the rotor cagethat helps reduce turbidity and greatly facilitates wind or water exhaust from the system.

U.S. Patent Application Publication No. 2002/0070558, published Jun. 13, 2002, to K. Johann, discloses a windmill for converting wind energy into electrical power and supplying it to a power grid, comprising a blade assembly, a generatorhousing, and a main shaft operatively coupled between the blade assembly and generator housing. The generator housing contains a first generator having a first generator output and a second generator having a second generator output. A hydraulic strutsupports the generator housing and allows angular adjustment thereof. A hydraulic pump selectively pressurizes the hydraulic strut to effect adjustment thereof. A braking system is selectively actuable to slow rotation of the main shaft. A flyweightassembly and a four position speed sensing switch together detect rotational speed of the main shaft, selectively connect the generators with the main shaft, and selectively activate the braking system and hydraulic pump as appropriate according to thespeed detected by the speed sensing switch.

The above patent applications do not describe a means for utilizing multiple generators and/or a variable wind dam for controlling windmill vertical rotor shaft rotational speed to thereby provide a substantially constant frequency output alongwith an increased efficiency wind power electrical generator. The solutions to the above-described problems have been long sought without success. Consequently, those skilled in the art will appreciate the present invention that addresses the above andother problems.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved windmill electrical power generator.

Another object of the present invention is to provide a plurality of generators interconnected with the windmill in a manner whereby the generating capacity thereof is controlled in a manner to provide a substantially constant windmill shaftrotational speed.

Another object of the present invention is to provide moveable air foils operable for controlling the wind flow to windmill blades in the power producing part of their rotation.

These and other objects, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims. However, it will be understood that above listed objects and advantages ofthe invention are intended only as an aid in understanding aspects of the invention, are not intended to limit the invention in any way, and do not form a comprehensive list of objects, features, and advantages.

Accordingly, the present invention provides a wind generator for generating electricity in response to wind flow comprising one or more elements such as, for instance, a vertical or horizontal axis windmill comprising a shaft and a plurality ofblades secured thereto, at least two moveable air foils which form an adjustable size opening for directing a selectable amount of the wind flow into the plurality of blades, a base supporting the at least two air foils, the base being rotatably mountedfor orienting the at least two air foils into the wind flow, a ring gear mechanically affixed to the shaft, and/or a plurality of generators arranged for mechanical interconnection with the ring gear. The entire unit just described can also be set uphorizontally to minimize the overall height of the unit.

The plurality of generators may comprise moveable mechanical elements operable for mechanically engaging and for disengaging the plurality of generators with the ring gear. The wind generator may further comprise a control operable formaintaining a substantially constant rotating frequency of the shaft even as a speed of the wind flow changes. This is accomplished by selectively varying a generating power capability of the plurality of generators connected to the shaft through thering gear. The control is preferably also operable for controlling wind flow to the plurality of blades through the adjustable size opening in coordination with generator power capability for maintaining the substantially constant rotating frequency ofthe shaft even as a speed of the wind flow changes.

In one embodiment, the plurality of generators may remain mechanically connected to the ring gear and the control is operable for controlling a stator current to thereby control the generating power capability. In another embodiment, the windgenerator may further comprise moveable mechanical coupling elements such that the control is operable for mechanically coupling and uncoupling each of the plurality of generators from the ring gear to thereby control the generating power capability.

The wind foils are positioned and shaped to direct the wind flow substantially only to blades which are in a portion of a rotation to be moving in the same direction of the wind flow and to block wind flow to blades which are in a portion of therotation to be moving in the opposite direction of the wind flow.

A method for operating the windmill for generating electricity comprises one or more steps such as, for example, connecting the plurality of generators such that a generating capacity thereof can be varied to thereby vary resistance to rotationof the axis, mounting the one or more moveable wind foils for controlling an amount of wind flow directed at wind blades in a power producing portion of a rotation around the axis, monitoring a rotational speed of the axis, and/or controlling thegenerating capacity and a position of the moveable wind foils responsively to the rotational speed of the axis to maintain a substantially constant rotational speed.

The method may further comprise mounting a flywheel to the axis to stabilize the rotational speed and/or may further comprise providing a ring gear on the flywheel for interconnection with the plurality of generators. The generating capacity maybe varied by engaging or disengaging a respective rotor for each of the plurality of generators with respect to the ring gear. The method may further comprise varying the one or more moveable wind foils each time a respective of the plurality ofgenerators is engaged or disengaged with respect to the ring gear.

In one embodiment, the method may further comprise providing at least two wind foils which are relatively moveable with respect to each whereby a variable opening is formed therebetween for controlling the amount of wind flow directed at windblades in the power producing portion of their rotation around the axis. The generating capacity may also be varied by controlling a stator current for each of the plurality of generators.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction withthe accompanying drawings, wherein like reference numerals refer to like parts and wherein:

FIG. 1A is a diagrammatic view showing a wind dam comprising a windmill wherein the wind funnel structure is substantially open to wind flow in accord with the present invention;

FIG. 1B is a diagrammatic view showing the wind dam of FIG. 1A with a windmill wherein the wind funnel structure is in the process of closing to restrict wind flow in accord with the present invention;

FIG. 1C is a diagrammatic view showing the wind dam of FIG. 1B with a windmill wherein the wind funnel structure continues to close to restrict wind flow in accord with the present invention; and

FIG. 1D is a diagrammatic view showing the wind dam of FIG. 1C with a windmill wherein the wind funnel structure is substantially closed to restrict wind flow in accord with the present invention.

FIG. 2 is a perspective view showing a vertically oriented wind dam with a windmill and a variable opening wind funnel structure in accord with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is shown wind dam generator 10 which uses wind as its source of power to generate electricity for public use. As shown in FIG. 2, wind dam generator 10 has an elongated cylindrical shape. Blades 12 may bemade of fiberglass-reinforced plastics or any other suitable material and mounted in the center on an axle 14. On either side of the blades 12, on the front end of wind dam generator 10, which is oriented toward the incoming wind 15, are two wind funnelair foils 16 and 18, forming the wind dam. In one embodiment, both wind funnel air foils 16 and 18 are relatively moveable in orientation with respect to each other and axle 14. However, either air foil funnel structure 16 or 18 could be fixed with theother air foil funnel structure being relatively moveable, if desired. Thus, funnel structures 16 and 18 are relatively moveable with respect to each other so they can be opened or closed to moderate the amount of wind passing through the generator (seeFIG. 1A, FIG. 1B, FIG. 1C, and FIG. 1D).

As noted, air foils 16 and 18 form a funnel that guides the wind to windmill blades 12. Preferably, air foil 18 may have an internal wind blocking circumference 19 that covers some blades 12 to prevent counter forces acting on the blades whichwould go against the direction of rotation as indicated by arrow 17. Thus, the arc of internal wind blocking circumference 19 may comprise about sixty to one hundred degrees of the rotational circle. Flow of the wind against those blades covered byinternal wind blocking circumference 19 would have counter forces produced on axel 14 if the wind were to encounter them. On the other hand, the remaining blades which are not covered by internal wind blocking circumference 19 are in the power producingpart of their rotation. By directing air flow onto these blades, the power produced in axel 14 is maximized.

Air foil 18 at least would include guide surface 21 which extends radially outwardly from the outermost reach of blades 12 to scoop out additional wind and direct that wind to the power producing blades. Conceivably guide surface 21 may also besufficient to block the air flow significantly without the use of blocking surface 19, if desired.

Air foil 16 may preferably be used as the other side of the funnel to scoop in air from a large radius and direct the air to the power producing blade as indicated in FIG. 1A. As necessary, the opening through which the air flows between airfoils 16 and 18 can be greatly restricted as indicated in FIG. 1B, FIG. 1C, and FIG. 1D. As indicated, the two air foils 16 and 18 produce a variable opening funnel which can selectively either introduce air from a region of air with a diameter greaterthan the radius of blades 12 which is preferably applied only to the power producing blades, or can be narrowed to any extent including air from a region of air much smaller than the diameter of the radius of blades 12 for introduction preferably to thepower producing blades. Control 23 may be utilized to monitor axel rotational speed for opening and closing air foils 16 and 18 as desired.

At the base of blades 12 is, in one embodiment, large gear flywheel 20. Flywheel 20 serves two purposes; one is to limit the change in speed due to wind gusts, and the other is to provide a support for ring gear 28 which interconnects withmultiple generators, and if desired, allows multiple generators, such as generators 22 and 24, to be mechanically connected/disconnected to thereby come on and off line as the wind speed changes. In a preferred embodiment, wind dam generator 10 wouldtypically comprise four to eight generators. Mounting the generators on the ground allows use of much larger generators than those that are mounted on the shaft as is used in the prior art.

If engageable/disengageable mechanical interconnections are utilized as in one embodiment of the invention, then generator shaft 26 could be connected by a universal joint to thereby permit raising and lowering shaft 26 for interconnection withgear 28 of flywheel 20. As one possible alternative, generator 22 could be slidably mounted to thereby move gear 30 into engagement with ring gear 28. Synchromesh gear arrangements, as could be provided in various ways, would permit smooth engagementand disengagement. As another possibility, the generators may be connected through a clutch. In yet another embodiment, all generators could remain connected mechanically through fly wheel 20 or by other mechanical connections and theengagement/disengagement of the generator could be effected electrically by controlling the stator current of each generator to thereby control the physical resistance encountered by each generator shaft 26, as discussed in more detail hereinafter. However the generators are interconnected and operated, the generators are preferably utilized as a means for maintaining a constant shaft speed. Constant shaft speed results in a constant frequency output of the power, which is desirable especially ifpower is applied to a power grid.

Wind dam generator 10 is preferably mounted on controlled rotating platform 32 that would keep the wind dam generator 10 pointing into the wind (see FIG. 2), preferably by automatic control with control 23. Base 34 supports the entire structure.

One embodiment of a method of operation for wind dam generator 10 is as follows; when the wind reaches a minimum speed to provide the desired frequency of operation with airfoils 16 and 18 open, (typically 6 to 10 m.p.h.) the first asynchronousgenerator, such as generator 24, would be connected to gear 28 on flywheel 20. This would start producing the minimum rated amount of electricity for the generator at the desired frequency of operation, e.g., 50 Hz or 60 Hz. As the wind increases inspeed, airfoils 16 and 18 on either side of the blades would start to close, to keep the generator turning at a constant speed (to produce alternating current (AC) electricity at the constant desired frequency). When the wind reaches a particular higherspeed, airfoils 16 and 18 on either side would open, allowing more wind to enter the blades and, at the same time, another generator, such as generator 22, would be mechanically connected to the gear at the base of the unit. This process would continueas the wind speed increases. As indicated above, preferably from about four to eight generators would be available. The airfoils would continue to close together until another threshold was reached, then they would open and another generator would beadded. This process would use wind energy much more efficiently than the current large wind blade style. It would be able to produce electricity at a lower wind speed, and continue to efficiently extract energy from much higher wind speeds. Thefrequency of electricity produced would be kept at a more consistent value while the amperage increased or decreased along with the wind. The order of implementation for the generators would preferably be in a circular queue. The first would be added,then the second, then the third, as the wind increases. When the wind starts to decrease, the first generator would be removed. If the wind increased, the fourth generator would be implemented. This would continue in a circular fashion until it cameback around to the first generator. This process would ensure that all generators would statistically get the same amount of use and that a generator could be taken off line for maintenance without affecting power generation. It also optimizes theefficiency of the unit. Cooling would be done at the same rate as the addition and deletion of generators to implement only the cooling that is required. The optimum number of generators for the system would be determined through wind characteristicsof the location of the wind dam generator 10 and through experimentation.

Control 23 may be utilized with suitable programming for monitoring wind speed, and the number of generators, and the opening of air foils 16 and 18, and for orienting the air foils towards into the wind direction by rotating base 34. Thus.,control 23 could be programmed to monitor axel rotational speed and adjust the other factors accordingly in a feedback circuit.

As the wind speed increased, so would the number of generators. Instead of wasting the extra energy of the higher wind speeds, it would be collected by another generator. The wind dam generator 10 would not be limited by the power rating of asingle generator. It would be able to maintain a 30% to 40% efficiency over a broader range of wind speeds.

In another embodiment, all generators would remain connected with respect to flywheel gear 28 or other gearing. Initially, the stator current in each generator would be zero or near zero and the generators effectively disconnected because withzero current, and assuming no magnetic residual, there is no resistance except friction resistance. The additional rotating shafts would also provide a flywheel effect as discussed above for reducing minor variations in shaft speed. With the wind foilsopen, once the shaft came up to the desired frequency of rotation, then stator current would be applied to one or more generators thereby controlling the torque or force required to rotate the generator shaft, and the force acting against rotation ofaxel 14. In this case, control 23 may comprise a feedback system which would then control the stator current based on the rotational speed of axel 14. As axel speed starts to drop, the stator current would be reduced to permit easier rotation of axel14 thereby maintaining the rotational frequency. As axel speed starts to rise, an increase in stator current would increase the rotational resistance to maintain the shaft rotational speed. The current output would vary accordingly. If the windbecomes too high after all generators are operating at maximum, then air foils 16 and 18 would begin closing to reduce the wind to maintain the frequency. Items 36 through 38 may symbolically represent sensors such as wind direction sensors, air speedsensors, air foil position sensors, rotatable base 32 position sensor, axel rotation speed sensor, generator sensors, other desired sensors and actuators, and could also represent additional generators that may preferably be utilized.

The advantages of the present invention include a smaller footprint than the standard large blade generators, and a much more intelligent, efficient generator that could produce more power over a broader range of wind speeds. As anotheradvantage, the entire wind dam generator can be built with either a vertical or horizontal shaft or actually a shaft with any orientation. If built with a horizontally oriented shaft, for instance, the overall height of the unit can be greatlyminimized. Moreover, a horizontal blade shaft could be very long, but the unit would still have a minimal height due to the fact that the entire unit is on its side. Therefore, the present invention may be used in places where height is an issue and inplaces where height is not an issue.

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in theart within the principle and scope of the invention as expressed in the appended claims.

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