Wind turbine drive train

A wind turbine having a tower having a top end and a bottom end; a first eccentric mechanism connected to a turbine rotor, the turbine rotor at the top end of the tower; a second eccentric mechanism connected to an electric generator, the electric generator being at the bottom end of the tower; and a plurality of tensile links connecting the first and second eccentric mechanisms.

TECHNICAL FIELD

The disclosure herein relates to devices for transmitting rotational energy from the input rotor shaft of a turbine to an electricity generator. Turbines are used to harvest energy from a moving fluid and convert it into other forms of energy, often electricity but alternatively kinetic or potential energy. Turbines that harvest energy from atmospheric wind do so by transmitting a rotational energy from the rotor of the turbine to an electrical generator. Rotational energy can be transmitted by direct coupling to the generator or indirectly through drivetrain components, such as gear sets or transmissions.

BACKGROUND

Some of the largest turbines on earth are wind turbines and, in order to access enough wind to operate, must be placed at the top of tall towers or structures. These structures must be slender, so as to not disrupt the flow of wind through a turbine, and strong, to endure the forces exerted by the wind on the blades of the turbine. While a tall tower improves the performance of a wind turbine, the taller the tower, the more difficult it is to place and service machinery at the top of the tower.

Commercial wind turbines produce thousands of watts (kW), if not, millions of watts (MW) of electricity. A generator large enough to produce these amounts of electricity is both large and heavy, weighing many tons. Current designs of electricity-generating wind turbines place the generator at the top of the tower, close to the rotor. The generator is so large and heavy that large and expensive cranes and crane systems are required to construct commercial wind turbines. Accordingly, a significant portion of construction costs are associated with lifting the generator to the top of a wind turbine tower. This problem is compounded for offshore turbine installations.

Additionally, wind turbines must be maintained on a regular basis to ensure they remain productive and efficient. Because the rotor, gear sets, transmission, and generator of a typical wind turbine are all located the top of the wind turbine tower, access is limited and maintenance is expensive and often dangerous. The device described herein addresses the high expense of construction and maintenance of existing wind turbines by relocating the generator at or near the bottom of the wind turbine tower. An innovative power transmitting device is used to transfer the rotational energy from the rotor at the top of the tower to the generator at or near the bottom of the tower.

Wind turbines can be of two general designs, direct drive and indirect drive. Direct drive wind turbines have a direct connection between the wind turbine rotor and the generator whereby the generator is rotated at the same speed as the rotor. Indirect drive turbines have a gear set or transmission between the shaft rotated by the rotor and the input shaft of the generator. The gear set can have a fixed or variable gear ratio to control the rotational speed of the rotor and/or the generator.

Additional shortcomings to the prior art can be attributed to the slow speed (˜15 rpm) at which the rotor of a wind turbine rotates. In the case of a direct drive wind turbine, the generator must be designed with additional poles to produce a sufficient amount and quality of electrical energy, which substantially increases the weight and cost of the generator. In the case of indirect drive wind turbines, the reliability and serviceability of the gear sets is a cause for concern because they are not easily accessible due to their location in a nacelle, directly behind the rotor, at the top of the wind turbine tower. However, indirect drive wind turbines can have an advantage when placed on floating, off-shore installations due to their smaller generators and lower overall weight.

SUMMARY

The needs set forth herein as well as further and other needs and advantages are addressed by the present embodiments, which illustrate solutions and advantages described below.

There is a need for a device that efficiently transfers energy from the rotor of a wind turbine at the top of a wind turbine tower to a generator that is closer to the ground than current designs. Placing the generator closer to the ground will help reduce costs associated with maintenance and construction of the wind turbine as well as reduce overall weight.

One embodiment of the wind turbine has a tower, the tower having a top end and bottom end. The wind turbine also has a first eccentric mechanism connected to a turbine rotor, the turbine rotor at the top end of the tower. The wind turbine has a second eccentric mechanism connected to an electric generator, the electric generator at the bottom end of the tower and a plurality of tensile links connecting the first and second eccentric mechanisms.

Another embodiment of the wind turbine has a first eccentric mechanism where the first eccentric mechanism is a cam-follower mechanism.

Another embodiment of the wind turbine has a cam-follower mechanism where the cam-follower mechanism has a cam shaft with at least one cam profile, having a plurality of cam lobes driven by the turbine rotor, and a plurality of cam followers each driven by the plurality of cam lobes.

Another embodiment of the wind turbine has a plurality of tensile links where each tensile link of the plurality of tensile links has a first end connected to a cam follower of the plurality of cam followers.

Another embodiment of the wind turbine has cam lobe heads where each cam lobe has at least one cam lobe head and each cam lobe head of the cam shaft is separated by a phase angle offset measured about an axis running parallel to a length of the cam shaft.

Another embodiment of the wind turbine has a phase angle where the phase angle offset is 360/(n*m) degrees, wherein n is equal to the number of tensile links of the plurality of links and m is equal to the number of cam lobes per cam profile.

Another embodiment of the wind turbine has a second eccentric mechanism where the second eccentric mechanism is a swashplate mechanism.

Another embodiment of the wind turbine has a swash plate mechanism where the swashplate mechanism has an output shaft and a plate, the output shaft is connected to a generator, and the plate is connected to the plurality of tensile links.

Another embodiment of the wind turbine has a plate where the plate has connection locations disposed along a perimeter on the plate, the perimeter is disposed around the output shaft, and the plurality of tensile links are connected to connection locations.

Another embodiment of the wind turbine has a perimeter where the perimeter is a circle in the plane of the plate.

Another embodiment of the wind turbine has connection locations where the connection locations are disposed in equal distances from each other along the perimeter.

Another embodiment of the wind turbine has a first eccentric mechanism where the first eccentric mechanism and turbine rotor rotate about a rotational axis, the first eccentric mechanism is connected to the tower via a first yaw mechanism, and the first yaw mechanism allowing the first eccentric mechanism to rotate in relation to the tower and about an axis oblique or perpendicular to the rotational axis of the first eccentric mechanism.

Another embodiment of the wind turbine has a second eccentric mechanism where the second eccentric mechanism is connected to the tower through a second yaw mechanism, and the second yaw mechanism allows the second eccentric mechanism to rotate in relation to the tower and about an axis parallel to the length of the tower.

Another embodiment of the wind turbine has a first yaw mechanism where the first yaw mechanism position is adjusted in response to a change in the position of the second yaw mechanism position or vice versa.

Another embodiment of the wind turbine has a first yaw mechanism where the first yaw mechanism and the second yaw mechanism are one mechanically connected mechanism.

Another embodiment of the wind turbine has tensile links where the tensile links are comprised of carbon fibers.

Another embodiment of the wind turbine has a cam profile where the cam profile has a plurality of lobes.

One embodiment of a wind turbine has a tower having a top end and bottom end; a first eccentric mechanism connected to a turbine rotor, the turbine rotor at the top end of the tower; a second eccentric mechanism connected to an electric generator, the electric generator at the bottom end of the tower; a plurality of tensile links connecting the first and second eccentric mechanisms; a first yaw mechanism; and a second yaw mechanism. The wind turbine has a first eccentric mechanism where the first eccentric mechanism is a cam-follower mechanism and the cam-follower mechanism has a cam shaft with at least one cam profile, with a plurality of cam lobes driven by the turbine rotor, and a plurality of cam followers each driven by the plurality of cam lobes. Each tensile link of the plurality of tensile links has a first end connected to a cam follower of the plurality of cam followers. Each cam lobe has a cam lobe head and each cam lobe head of the cam shaft is separated by a phase angle offset of 360/(n*m) degrees measured about an axis running parallel to a length of the cam shaft, wherein n is equal to the number of tensile links of the plurality of links and m is equal to the number of cam lobe heads per cam profile. The second eccentric mechanism is a swashplate mechanism and the swashplate mechanism has an output shaft and a plate, the output shaft is connected to a generator, and the plate is connected to the plurality of tensile links at connection locations. The plate has connection locations disposed at equal distances along a perimeter on the plate and the perimeter is disposed around the output shaft.

Another embodiment of the wind turbine has a first eccentric mechanism and a turbine rotor where the first eccentric mechanism and the turbine rotor rotate about a rotational axis.

Another embodiment of the wind turbine has a first eccentric mechanism where the first eccentric mechanism is connected to the tower via a first yaw mechanism. The yaw mechanism allows the first eccentric mechanism to rotate in relation to the tower and about an axis oblique or perpendicular to the rotational axis of the first eccentric mechanism. The second eccentric mechanism is connected to the tower through a second yaw mechanism. The second yaw mechanism allows the second eccentric mechanism to rotate in relation to the tower and about an axis parallel to the length of the tower.

DETAILED DESCRIPTION

The present teachings are described more fully hereinafter with reference to the accompanying drawings, in which the present embodiments are shown. The following description is presented for illustrative purposes only and the present teachings should not be limited to these embodiments.

In compliance with the statute, the present teachings have been described in language more or less specific as to structural and mechanical features. It is to be understood, however, that the present teachings are not limited to the specific features shown and described, since the apparatus, systems, and methods herein disclosed comprise preferred forms of putting the present teachings into effect.

For purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding. In other instances, detailed descriptions of well-known devices and methods are omitted so as not to obscure the description with unnecessary detail.

To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, Applicant does not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

A notable advantage to the disclosed device is the reduction of overall weight in a wind turbine assembly and the reduction of weight at the top of a wind turbine assembly. This is particularly useful for off-shore, floating wind turbine installations. Further advantages are ease of maintenance of major working components because the disclosed device moves the generator closer to the ground at the bottom of the wind turbine tower. The disclosed device also removes the need to maintain a gear box near the wind turbine rotor because the disclosed device does not require a gear box connected to the wind turbine rotor, although one can be added if desired. A further advantage of the disclosed device is that if a speed change is required, then a gear box can be placed closer to ground level near the generator instead of near the wind turbine rotor. Alternatively, a gear speed increase can be realized with a multi-lobe cam profile incorporated with a minimal weight penalty at the top of the wind turbine tower.

Referring toFIG. 1, a wind turbine1system is shown having a wind turbine rotor10, wind turbine blades11, a driveshaft12, cam profiles13, tension members14, a swash plate15, an output shaft16, generator17, tower18, tower base19, and nacelle20.

The wind turbine1can have two or more turbine blades11connected to the rotor10, about which the turbine blades11rotate. The rotor10can be connected to a cam profile13through a drive shaft12. The rotor can also be connected to a cam profile13such that rotation of the rotor10rotates the cam profiles13.

Although an embodiment of the disclosed wind turbine drive train would have the cam profiles13directly driven by the rotor10, there can be a gearset positioned between the driveshaft12and the cam profiles13such that the cam profiles13rotate faster than the rotor10. In turn, torque transmitted from the rotor10to the cam profiles13can be decreased. Torque transmitted to and cam profile13shape can be optimized based on the required rotational speed of a generator and the expected or observed rotational speed of the rotor10.

The cam profiles13can act on tension members14. The lobes of the cam profile13can pull the tension members14through cam followers36to transmit a force from the rotor10to the tension members14. The cam profiles13each can have cam followers36that follow an eccentric path around the cam profile13. The cam followers36can be connected to the tension members14such that the tension members14are pulled and released as the cam followers36each follow the eccentric path around each cam profile13. The tension members14can be raised and lowered according to the movement of cam followers36along cam profiles13.

The lobes of the cam profile13can have a lobe spacing such that tension is applied to each tension member14sequentially rather than simultaneously over the course of a rotation of the wind turbine rotor10. For example, in a case where a wind turbine1has three tension members14, a full rotation of the rotor10can be divided into 360 degrees and can result in a tension force being applied to a first member starting at 0 degrees, a tension force being applied to a second tension member14starting at 120 degrees, and a tension force being applied to a third tension member14starting at 240 degrees. Such an arrangement is a system where each tension member14is cyclically tensioned, moved, and released over the course of a rotation of the wind turbine rotor10. The lobes of each cam profile13are situated such that the cyclical tension application to each tension member14is out of phase with each other and a smooth application of force to the tension members14is achieved.

In the case of more tension members14, the cam profile13quantity and spacing can be adjusted such that tension is applied to each member along individual cycles that are phased equally about a full rotation of the rotor10. A complete cycle where a tension member14is tensioned, then un-tensioned is a tension cycle. Additionally, the tension cycles of the tension members14can be phased equally about multiple rotations of the rotor10. For example, when a gear reduction mechanism is placed between the rotor10and the cam profiles13. In this case, the rotor would spin more than one rotation per a single rotation of the cam profiles13. Conversely, multiple tension cycles per tension member14can be equally phased over one rotation of the rotor10; this corresponding to a gear ratio increase.

The tension members14can be connected to a swash plate mechanism having a swash plate15and an output shaft16. The tension members14can be connected to portions of the swash plate15such that each tension member14acts on a different point of the swash plate15. The tension members14can also be connected to different points on the swash plate15along a perimeter around the output shaft16. For maximum leverage, the tension members14can be connected to an outer perimeter or circumference of the swash plate15.

Referring toFIGS. 1, 3, and 4. The tension members14can be tensioned in sequence going around a perimeter surrounding the output shaft16. For example, a round swash plate15can have three tensioning members14attached at equally-spaced points around a circumference of the swash plate15. As the rotor10is turned, the cam profiles13are situated such that a tension force is applied to a first tensioning element14, applying a pulling force to the edge of the swash plate15in a direction parallel to the output shaft16. This causes the swash plate15to tilt about an axis perpendicular to the longitudinal axis of the output shaft16and perpendicular to a line extending from the same longitudinal axis to the connection point of the first tension member14to the swash plate15. An amount of time after a force is applied to the first tensioning member14, but before the first tensioning member14reaches the top of its travel, a force is applied to a second tensioning member. The second tensioning member14being adjacent to the first tensioning member14along the perimeter in the direction of the rotation of the output shaft16. The force applied to the first tensioning member14is decreased and the second tensioning member14is pulled to the top of its travel, tilting the swash plate15about an axis perpendicular to the longitudinal axis of the output shaft16and perpendicular to a line extending from the longitudinal axis to the connection point of the second tension member14to the swash plate15. This process continues with the third tensioning member14, and then back to the first tensioning member14, and so on. This process causes the swash plate to move such that the highest point of the circumference of the swash plate travels around the circumference of the swash plate15in a circular oscillation.

The swash plate motion described above can cause the output shaft16to rotate. There can be a mechanism between the swash plate15and the output shaft16that transfers a pulling force on the swash plate15to a rotational force on the output shaft16. The above process of sequentially applying tension to the tensioning members14connected to the swash plate15can cause the swash plate15to move with a cyclical “wobble” whereby when the swash plate15is tilted in a direction about the output shaft16, the output shaft16is rotated a fraction of a full rotation. This “wobble” can also be described as a circular oscillation. The device, by continuously changing the direction in which the swash plate15is tilted, continuously rotates the output shaft16.

In order to achieve a rotation of the output shaft16, the swash plate15can be rotationally fixed about the rotational axis of the output shaft16. This can be achieved by links23fixing the swash plate15in a rotational direction while allowing the swash plate15to tilt in the directions stated above. Examples of securing links23include Watt-link mechanisms and Chebyshev-link mechanisms.

The output shaft16can be connected to a generator17. The generator17can be mounted at or near the bottom of the wind turbine tower18. As the swash plate15is cyclically tilted as described above, the output shaft16can be rotated and transfer rotational force to the generator17to produce electricity. The generator17can be specified depending on the amount and type of electricity required. Generating capacities can be as small as a few watts up to multiple megawatts, although currently commercial generators are specified to produce electricity in the range of kilowatts to megawatts.

There can be a direct connection between the output shaft16and the generator17whereby one rotation of the output shaft16rotates the generator17one rotation. Alternatively, there can be a gear box or transmission device with an increasing gear ratio. The device can either convert one rotation of the output shaft16into multiple rotations of the generator with an increasing gear ratio, or the same device can reduce one rotation of the output shaft16to less than one rotation of the generator17with a reducing gear ratio, although not limited thereto. The transmission or gear box device between the output shaft16and the generator17can have a variable gear ratio such that the ratio of the rotational speed of the output shaft16and the generator17can be varied using a control device. The control device can be programed to change the output shaft/generator rotation ratio such that the rotation speed of the generator17is maintained within a window. The window can be defined by a minimum generator rotational speed and a maximum generator rotational speed.

The tension members14can have a tensioning mechanism such that slack is removed from the tension members14when the cam profile13and cam follower36release the tension member14. This anti-slack mechanism can be a spring mechanism, screw mechanism, clamp mechanism, hydraulic mechanism, or any other mechanism known in the art for removing slack from a linear tensile element.

A wind turbine must face into the direction the wind is blowing to be most efficient. To accomplish this, wind turbines include a yaw mechanism that allows the nacelle on top of the wind turbine tower to rotate, thereby rotating the wind turbine rotor to face the direction of the wind. The wind turbine1can also rotate the nacelle20to face the rotor10into the wind. However, additional considerations must be made for the drivetrain mechanism at the bottom of the wind turbine tower18. The wind turbine1can have a yaw mechanism21between the nacelle20and the tower18whereby the nacelle20can rotate about a longitudinal axis through the tower18. The yaw mechanism21can have a bearing about which the nacelle20rotates in relation to the center axis of the tower18. The yaw mechanism21can be driven by a spur gear set, worm gear, linear motors, belt drive, or any other mechanism known in the art for rotating a structure in relation to another. The yaw mechanism21can have a brake or other mechanism known in the art for securing the rotational position of a structure in relation to another.

Additionally, the generator17can also have a yaw mechanism22with which it can rotate simultaneously with the nacelle20. This yaw mechanism22can be of the same structure as the yaw mechanism21or separate. The yaw mechanism22can be a table or other similar structure upon which the generator17is secured. The yaw mechanism22can rotate at the same time as or in response to a rotation of yaw mechanism21and vice versa. The positioning of the yaw mechanisms21and22can be calculated and carried out in order to prevent additional or excessive tensioning and/or binding of the swash plate15, output shaft16, or tension members14.

Alternatively, there can be a yaw mechanism22built into the swash plate15whereby the fixing links23and the swash plate can rotate in relation to the output shaft16. Once the swash plate15yaw is repositioned, the yaw mechanism22can be secured such that the swash plate15can rotate the output shaft16without itself rotating. The yaw mechanism22can be driven by a spur gear set, worm gear, linear motors, belt drive, or any other mechanism known in the art for rotating a structure in relation to another. The yaw mechanism22can have a brake or other mechanism known in the art for securing the rotational position of a structure in relation to another.

The tension members14can have a mechanism to dampen vibration induced by wind, geographic movement, operation of the wind turbine1, or any other condition a wind turbine may be exposed to. Additionally, the tension members14can be designed such that they have inherent vibration or oscillation dampening characteristics to prevent destructive resonant frequency activity or persistent vibration. This in turn can prevent premature wear of wind turbine1components and failure.

Referring toFIG. 2A, a cam follower mechanism is shown such that the tension member is acted upon by a levered arm24. The cam profile13has three lobe heads26. In this configuration, a single rotation of the cam profile13pulls and releases the tension member14three times. Each tensioning of the tension member14can correspond to one “wobble” cycle of the swash plate15, which each can correspond to one rotation of the output shaft16. This configuration can act as a 3× speed increase instead of a gear box and save weight and cost. Costs are reduced because a cam mechanism would likely require less maintenance and a cam follower mechanism as shown inFIG. 2would likely contain fewer parts than a gear box would.

The cam follower ofFIG. 2Acan have a roller27that follows the contour of the cam profile13. As the roller27follows the cam profile13, the levered arm24can pivot about a fulcrum28, thus transmitting a force from the cam profile13to the tension member14. Alternatively, the roller27can also be a sliding surface made of self-lubricating material or made of material requiring a lubricating compound.

Referring toFIG. 2B, another cam follower is shown with a cantilevered arm29. This mechanism can have a roller27that follows a cam profile13. When a cam lobe head26acts upon the roller27, the cantilevered arm29raises and transmits a force to the tension member14. The cantilevered arm29can, through this motion, move the tension member14through an oscillating motion cycle in the direction of the length of the tension member14. As above, the roller27can also be a sliding surface. As above, the number of cam lobes increases the oscillation speed and thus multiplies the rotational speed of the generator without the need for a gear box.

Referring toFIG. 2C, another cam follower is shown with a plurality of levers forming an actuating linkage30. The cam profile13can rotate between rollers27, two opposing cam lobe heads26simultaneously acting to move the rollers27in opposite directions. The motion of the rollers27pulls the linkage31and32such that the attachment point33is moved. This movement applies force to the tension member14, moving it through an oscillating motion cycle in the direction of the length of the tension member14. As above, the roller27can also be a sliding surface. As above, the number of cam lobes increases the oscillation speed and thus multiplies the rotational speed of the generator without the need for a gear box. In this version of the mechanism a speed increase of 4× is realized.

Referring toFIG. 2D, another cam follower is shown with a piston-like frame34having a roller27, the frame moving within a channel35. When the cam lobe head26of the cam profile13acts on the roller27, the piston-like frame34is moved a distance within the channel35, thus applying force to a tension member14. The motion of the piston-like frame34moves the tension member14through an oscillating motion cycle in the direction of the length of the tension member14. As above, the roller27can also be a sliding surface. As above, the number of cam lobes increases the oscillation speed and thus multiplies the rotational speed of the generator without the need for a gear box.

A practical embodiment of the disclosed apparatus is described below.

A wind turbine1can have a rotor10with three rotor blades11. The rotor10can be connected to a drive shaft12that enters through the front of a nacelle20. The nacelle20contains three cam profiles13that are coaxially connected about their rotational axis to the drive shaft12. Each individual cam profile13is part of an individual one of three cam profiles. One rotation of the drive shaft12causes the cam profiles13to make a full revolution about their rotational axis. The cam profiles13are equally separated rotationally about their rotational axis such that the cam lobe heads26of each cam profile13are separated by 360/(n*m) degrees as measured about the rotation axis of the series of cam profiles13. “n” is equal to the number of tensile links and “m” is equal to the number of cam lobe heads per cam profile. In this embodiment, the cam profiles13are separated rotationally about their rotational axis such that the cam lobe heads26are separated by 40 degrees from adjacent cam profiles13as measured about the rotation of the series of cam profiles13. This embodiment realizes a 3× speed multiplication. The nacelle20is situated at the top of a wind turbine tower18.

Also, in the nacelle20are three cam followers36that follow the contour of the cam profiles13. Each cam follower36is assigned to each individual cam profile13. The cam followers36have a cantilevered arm29situated over the cam profiles13and have a roller27. The cantilevered arm29is actuated by the rotation of the cam profile13whereby when the cam lobe head26passes by the roller27, the cantilevered arm29is lifted.

Each cantilevered arm29of the cam follower36is connected to one tension member14at one end, although multiple tension members14can be connected to one follower. The tension member resembles a rope, cable, or rod. The tension member is made of carbon nanofiber composite, although other materials such as steel, lightweight metal alloys, composites, fibers, or any other material known in the art of tension member construction could be used.

The three tension members14extend down the wind turbine tower18and are each connected at their second end to a circular swash plate15. The three tension members14are each connected to a different point on the swash plate15. Because there are three tension members14in this case, each tension member14is connected to a point at or near the outer circumference of the swash plate15. Each of the connection points are equally separated along the outer circumference of the swash plate15, in this case each separated by an angle of 120 degrees measured around the center of the swash plate15. The tension member14are connected in positions around the circumference of the swash plate15such that according to the phase of the cam profiles13, the tension members14are moved axially up and down in a sequential order following the perimeter of the swash plate15.

The swash plate15has an output shaft16which is connected to a generator17. The swash plate15is connected to the output shaft16with a mechanism that rotates the output shaft16when the swash plate15is tilted in relation to the rotational axis of the output shaft16.

With cam profiles13equally phased about the rotation of the rotor10, wind pushes on the blades11of the wind turbine1, spinning the rotor10. This in turn rotates the driveshaft12and the cam profile13. The cam lobe heads26actuate the cam followers36which in turn move the tension members14axially parallel to their length. Due to the equally phased positions of the cam profiles13about the rotation of the rotor10, the axial motion of the tension members14is equally phased in relation to the rotation of the rotor10.

The equally phased motion of the tension members14causes the swash plate15to tilt in relation to the rotational axis of the output shaft16. As the rotor10rotates, the tension members14are actuated sequentially, rotating the direction of the tilt of the swash plate15in a circular direction about the axis of rotation of the output shaft16. This circular oscillation causes the output shaft to rotate the generator17input shaft. The rotation of the generator produces electricity.

The swash plate15is secured by links23preventing the swash plate15itself from rotating about the rotational axis of the output shaft16.

Both the nacelle20and the generator17are mounted on yaw mechanisms21and22. Both mechanisms allow their respective structures to rotate in relation to the tower18to face into the wind for optimum generating capacity and efficiency.

While the present teachings have been described above in terms of specific embodiments, it is to be understood that they are not limited to these disclosed embodiments. Many modifications and other embodiments will come to mind to those skilled in the art to which this pertains, and which are intended to be and are covered by both this disclosure and the appended claims. It is intended that the scope of the present teachings should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings.