Horizontal axis wind turbine with rotatable tower

A horizontal axis wind turbine with rotatable tower including nacelle and blades. The tower, the blades, and the nacelle are rotatable by following the shift of wind direction so as to align the blades to be facing with the wind direction for enhancing performances thereof. Also can eliminate the gearbox, as compared to the conventional horizontal axis wind turbine that the nacelle is not completely fixed with tower, the present invention is easy to manufacture with reduced costs.

(a) TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a horizontal axis wind turbine (HAWT) with a rotatable tower, and particularly to a wind turbine structure of which a tower, blades, and a nacelle are rotatable with the change of wind direction.

(b) DESCRIPTION OF THE PRIOR ART

The horizontal axis wind turbine (HAWT) is defined that axis of rotation is parallel to the ground surface, as shown inFIG. 1of the attached drawings. The conventional HAWT comprises a yaw gear and bearing assembly11, a tower12, and a nacelle13. The nacelle13comprises a gear box, a brake, and a generator . . . etc. Blades14are rotatably attached to the shaft in nacelle13. Reference numeral10indicates wind direction.

The tower12is fixed to the ground01while the nacelle13and the blades14are rotated with the change of wind direction10. Thus, the yaw gear and bearing assembly11that couples between the tower12and the nacelle13must bear the weights of the blades14and the nacelle13, as well as various forces and torques, including the wind power and the torque induced by a direction-change motor. This makes the mechanical structure of the yaw gear and bearing assembly11relatively weak and the manufacturing is difficult with added costs. In view of this issue, the present invention aims to provide a HAWT that can be easily manufactured with a reduced cost.

SUMMARY OF THE INVENTION

A primary objective of the present invention is to provide a HAWT with a rotatable tower, wherein the tower of the wind turbine, blades, and a nacelle are rotatable together in response to the shift of wind direction so as to make the wind power generation technique simple, the manufacturing easy, and the costs reduced.

In the HAWT with a rotatable tower described above, the tower and the nacelle of the HAWT are completely fixed together to make the mechanical structure quite simply, and the tower is fit in a hollow circular base mounted on the ground to have the weight thereof supported by one or plural steel spheres on the bottom of the base. Bearings or simply-structured movable steel rings or steel balls are arranged between a circumferential wall of the base and the tower. Outside the tower, a yaw motor and gearing or a simple winch, or instead, a tail fin, is provided. Thus, when the nacelle and the blades are rotated with the shift of wind direction, the tower is rotated too and various forces and torques acting upon the gearing and bearings are separated.

In the HAWT with a rotatable tower described above, the weights of the blades, the nacelle, and the tower are carried by the steel sphere(s) on the bottom of the base and the weight of the yaw gear box and motor or winch is supported by the ground.

In the HAWT with a rotatable tower described above, head wind power is taken by the base and the steel bearing rings thereof, and the torque of the yaw motor for changing direction is carried by a gear mounted to the tower.

In the HAWT with a rotatable tower described above, the nacelle can be arranged at a lower location by using power transmission apparatus to transmit power from shaft to electricity generator to reduce the bending torque applied to the tower, also can eliminate the gearbox, so as to make the wind turbine technique simple, the manufacturing easy, and the costs reduced.

In the HAWT with a rotatable tower described above, a tail fin is selectively used to replace the yaw motor and the tail fin is made of metal plates and/or plastic boards, or made of canvas and/or plastic sheets so as to be automatically rolled up in case of strong winds to avoid receiving the strong force of the winds.

In the HAWT with a rotatable tower described above, the main rotational shaft can be provided with support strut that are supported by rollers for supporting front and rear ends of the shaft.

In the HAWT with a rotatable tower described above, the base can be mounted to a floatable platform on sea surface and the platform is anchored by a cable attached to a submarine foundation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings and in particular toFIG. 2, the present invention provides an arrangement where the nacelle13and the tower12are completely fixed together so as to eliminate the yaw gear and bearing assembly11that is adopted in the conventional horizontal axis wind turbine (HAWT) illustrated inFIG. 1and thus making the mechanical structure quite simply so that the manufacturing of the HAWT become easy and the costs reduced.

A base15is made of steel tube buried under the ground01(or alternatively mounted to a floating platform, which will be described later). The tower12is fit into the base15and rests on a steel balls assembly16, which may comprise a single steel balls16or a plurality of steel balls16. The steel balls16is supported by a base board23and is retained by a retention ring24. The retention ring24can be set along an outer circumference or at a center to work with a plurality of steel balls16. Bearings or rotatable flat steel rings with round arc in edges or steel balls17A,17B are arranged between the tower12and a circumferential wall of the base15to accommodate the rotation of the tower12and the bearings17A,17B are respectively retained in positioned by support rings22A,22B that are fixed to the tower12.

The outside of base15can be surrounded by concrete also the lower part of hollow tower12can be filled by hard materials such as cement to increase the strength.

A gear18is mounted to the tower12and is driven by a yaw gear and a yaw motor19in response to detection of wind direction by a wind vane or an anemometer (not shown) to rotate the tower12in order to align the blades14to be facing with wind direction.

With the above arrangement, the forces and torques that the conventional yaw gear and bearing assembly11must take can be separated as follows:

(1) The weights or gravities of the nacelle13, the tower12, and the blades14are carried by the steel sphere(s)16and the base board23.

(2) The weight of the yaw gear box and the motor19is supported by the ground or other support frames.

(3) Head wind power is taken by the bearings17A,17B and the base15.

(4) Torque for changing direction is carried by the gear18.

Thus, the stress induced in each component is made relatively low, and without the 11 yaw gearing and bearing ofFIG. 1will make the mechanical structure simple and the manufacturing cost reduced.

Referring toFIG. 3, another embodiment that replaces the yaw gear box and the motor19in accordance with the present invention is shown, wherein a winch30that winds up a steel cable31and rotates forwards/backward in response to a signal indicating wind direction or alternatively and/or additionally, a tail fin20is used to as the replacement. The tail fin20or the winch30rotates the tower12with the wind direction so as to align the blades14with the wind direction. In case that the tower12has been rotated for many turns that cannot be tolerated by an electrical cable connected thereto, the winch30is automatically actuated in such a way to return the tower12back to the home position. The tail fin20is mounted to the tower12through support frames21A,21B. The tail fin20is made of metal plates and/or plastic boards, or made of canvas and/or plastic sheets so as to be automatically rolled up in case of strong winds that have a speed greater than 30 n/sec and be protected against damage caused by the winds.

Referring toFIG. 4, the nacelle13can be selectively arranged at a lower location, such as mounting the nacelle13on a support frame21A. The main rotational shaft25is supported by a bearing26or multiple bearings on the tower12. A power transmission apparatus such as gear wheel or pulley . . . etc.27is fixed to the main rotational shaft25and is coupled to the nacelle13through a gear chain or a cable28for transmitting of power to the nacelle13for electricity generation. In this way, the torque that the nacelle13applied to the tower12can be much reduced and rotational speed can be increased without the traditional gear box in13nacelle.

Referring toFIG. 5, an arrangement can be made that multiple support frames or racks are used to support the primary rotational shaft25. In the illustrated arrangement, supplement towers12A,12B are arranged to support the main rotational shaft25through bearings26A,26B and stand on ground01by rollers29A,29B, in order to allow the tower12to freely rotate.

Referring toFIG. 6, the present invention provides an alternative arrangement where the base15is mounted on a floatable platform32that floats on sea surface02and is retained by a retention rack35. The floatable platform32is anchored by rope or cable that is fixed to a submarine foundation35to prevent floating away.

To summarize, the present invention combine the tower, the nacelle, and the blades attached to the nacelle together to allow the tower, the nacelle, and the blades of the HAWT to rotate with the shift of wind direction also it can be able to eliminate the gear box, so that the HAWT techniques are made simple, manufacturing easy, and cost reduced.