The present invention relates to a horizontal axis wind turbine more particularly the invention relates to a yaw drive for horizontal axis wind turbine using friction drive.

BACKGROUND OF THE INVENTION

The yaw drive is an important part of the horizontal axis wind turbines. The main purpose of the yaw drive is to move the blades with rotor towards the wind direction.

For maximum efficiency, it is desired that the plane of rotation of the blade tips be maintained perpendicular to the wind direction, and when the wind direction is not horizontal, this requires azimuthal alignment for generating electricity more efficiently.

To achieve the above objects different type of yaw drive mechanism has been used but these yaw drives are having large yaw bearings. The cost and size of the yaw bearing are more. Therefore, there is a need for large space to accommodate large yaw bearing.

Therefore there is a need for small yaw bearing and new mechanism for turning the nacelle or blade assembly for horizontal axis wind turbine for generating electricity more efficiently.

OBJECT OF THE INVENTION

The main object of the invention is to keep the rotor blades facing towards the favourable wind direction or desired direction by means of yaw drive using friction drive.

Another object of the invention is to control the angular movement of the yaw drive by using solenoid actuation and simultaneous de-energizing / energizing of locking means thereby locking means with static supporting means, titling means with rotatable supporting means, connecting means and supporting means allowing the angular movement via itself to move the nacelle towards the favourable wind/desired direction. Yet another object of the invention is to replace / minimize the large yaw bearing into small yaw bearings.

Yet another object of the invention is to eliminate the need of separate yaw drive motor.

Further object of the invention is to configure the angular movement of the yaw drive like crawling action thereby controlled movement is achieved.

SUMMARY OF THE INVENTION

The present invention relates to a yaw drive for horizontal axis wind turbine using friction drive. The yaw drive of the present invention is used for maintaining plane of rotation of the blade tips towards favourable wind direction/desired direction. The yaw drive is controlled by actuation of moving means (9) and simultaneous energizing/de-energizing of locking means (5) thereby locking means (5) with static supporting means (3), turning means (6) with rotatable supporting means (1), connecting means (7) and supporting means (8) allowing the angular movement via itself to move the nacelle towards the favourable wind/desired direction. The locking means (5) is capable of maintaining the yaw drive/nacelle in same position at energized state/condition and allow the movement at de-energized state/condition. The moving means/solenoid (5) is capable of actuating the friction drive to create the resultant force for initiating angular movement. Each time the moving means (5) actuated to move the nacelle towards the favourable or desired wind direction.

BRIEF DESCRIPTION OF THE INVENTION

S.NO PART NAME PART NO

1. Rotatable supporting means / turn table 1

2. Small yaw bearing 2

3. Static supporting means 3

4. Housing for securing rotatable 4

supporting means

5. Locking means (first locking means 5a 5

and second locking means 5b)

6. Turning means (first turning means 6a 6

and second turning means 6b) 7. Connecting means 7

8. Supporting means 8

9. Moving means . 9

10. Main friction drive 10

11. Small friction drive 11

12. Generator 12

13. Rotor shaft connected to blade 13

Fig 1 illustrates the top view of the present invention.

Fig 2 illustrates the front view of the present invention which clearly shows smaller yaw bearing arrangement (2).

Fig 3 illustrates the actuation of friction drive by means of moving means (9).

Fig 4 illustrates flow chart which clearly describes the working method of the present invention. The above drawing illustrates the details has been given and will be provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments but that the same are provided simply for enablement and best mode purposes. The breadth and spirit of the present disclosure is broader than the embodiments specifically disclosed and encompassed within the claims eventually appended hereto.

DETAILED DESCRIPTION OF THE INVENTION

So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawing illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of the invention's scope as it may admit to other equally effective embodiments. One of the preferred embodiments of the invention discloses about a yaw drive for horizontal axis wind turbine using friction drive for maintaining plane of rotation of the blade tips towards favourable wind direction/desired direction. The yaw drive comprises of at least one rotatable supporting means (1) comprises of at least two small yaw bearing (2) below a bottom side, at least one static supporting means (3) comprises of a housing (4) for securing the rotatable supporting means (1) with at least two 85 smaller yaw bearings (2), at least a pair of locking means (5) electro magnetically engaged with diametrically opposite side of the static supporting means (3), at least a pair of turning means (6) rotatably secured via its centre axis with rotatable supporting means (1) and positioned equal distance from the centre rotating axis of the rotatable supporting means (1), a plurality of connecting means(7) pivotably connected between the locking means (5/5a/5b) and turning means (6/6a/6b), a plurality of 90 supporting means (8) pivotably extended from the pair of turning means (6), wherein the supporting means (8) is holding the generator (12), main friction drive (10) thereby providing leverage for turning action, wherein the locking means (5) is configured to alternatively and/or simultaneously engage and disengage with static supporting means (3) by means of electromagnetic means and the turning means (6) is configured to enable turning action via itself thereby the supporting means (8) angularly turning 95 the rotatable supporting means (1) with plurality of generator (12), main friction drive (10), rotor shaft (13) and blade of the nacelle towards the favourable wind direction, wherein the configuration of locking means (5) and turning means (6) combine to allow the turning movement of the nacelle towards the favourable wind/desired direction, and the movement is actuated by a resultant force due to titling between main friction drive axis and smaller friction drive axis and main friction drive torque. Wherein loo the resultant force acted on the smaller friction drive with generator is attached with the supporting means thereby the resultant torque turns the rotatable supporting means and nacelle.

Another embodiment of the invention discloses about configuration of electromagnetic locking means 105 (5), turning means (6) and moving means (9). The electromagnetic locking means (5) is configured to alternatively and/or simultaneously engage and disengage with static supporting means (3), the turning means (6) is configured to enable turning action via itself, and the moving means is configured to initiate the resultant torque through main friction drive (10) and small friction drive (11) thereby turning the supporting means (8) angularly with rotatable supporting means (1) with plurality of generator (12), no main friction drive (10), rotor shaft (13) and blade of the nacelle towards the favourable wind direction/desired direction.

Yet another embodiment of the invention discloses about movement of the nacelle. As per the present embodiment the locking means (5) and turning means (6) combine to allow the turning movement of 115 the nacelle towards the favourable wind/desired direction, and the movement is actuated by a resultant force / main friction drive torque due to titling between main friction drive axis and smaller friction drive axis. Yet another preferred embodiment of the invention discloses about the movement of the smaller friction drive (main friction drive (10) and small friction drive (11)) with generator assembly is actuated by the moving means (9). Wherein the moving means can be a solenoid or pneumatic or hydraulic apparatus or self-actuating means or combination thereof. The moving means can be controlled by means of a control means based on plurality of sensor inputs. Yet another preferred embodiment of the invention discloses about turning means (6). The turning means (6) comprises of a circular shape and hinged through its centre rotating axis. One end of connecting means (7) and supporting means (8) are connected with turning means (6) for enabling pivot action. The turning means is capable of rotate based on its centre rotating axis. Yet another embodiment of the invention discloses about a method for maintaining or moving plane of rotation of the blade tips towards favourable wind direction/desired direction by moving means (9) of friction drive to initiate/use the resultant force and simultaneously energizing/de-energizing of first and second locking means (5a&5b) , the method comprises the steps of;

Step 1: detecting a wind direction and comparing with predetermined wind condition Step 2: judging the rotating direction whether the first rotating direction or second rotating direction,

Step 3: actuating a friction drive via moving means (9) towards the first rotating direction or second rotating direction,

Step 4: de-energizing a first locking means (5a) or second locking means (5b),

Step 5: allowing the above de-energized locking means (5a or 5b) to move towards the first or second rotating direction,

Step 6: energizing the allowed locking means to lock at moved state,

Step 7: repeating the steps 3-6 until achieving predetermined position. wherein, if the judged result of step 2 and actuated direction of step 3 is first rotating direction, de- energizing a first locking means (5a) at step 4 and allow the movement in step 5, and energize in step 6 145 for lock, correspondingly following the above steps for second locking means (5b) to move towards the first rotating direction, wherein, if the judged result of step 2 and actuated direction of step 3 is second rotating direction, de- energizing a second locking means (5b) at step 4 and allow the movement in step 5, and energize in step 6 for lock, correspondingly following the above steps for first locking means (5a) to move towards 150 the second rotating direction, wherein, if the judged result of step 2 is no change, the step i is repeated until change in judged result. wherein, if the predetermined position is directly desired carrying out steps 3 to 7.

Further preferred embodiment of the invention discloses about a method for maintaining or moving plane of rotation of the blade tips towards favourable wind direction/desired direction by moving means 155 (9) of friction drive to initiate/use the resultant force and simultaneously energizing/de-energizing of first and second locking means (5a&5b), the steps involved in this above method are as below also refer fig 4 flow chart.

First detecting a wind direction and comparing with predetermined wind condition then judging the rotating direction whether the first rotating direction or second rotating direction. This is based on wind 160 direction or desired direction.

If the selected/desired direction is first rotating direction, first actuating a friction drive via moving means (9). The moving means can be a solenoid or pneumatic or hydraulic apparatus or self-actuating means or combination thereof. The moving actuates the movement between the main friction drive (10) and smaller friction drive (11) thereby developing a resultant force to initiate/move the yaw drive/ Actuation 165 of moving means will determine rotating direction (either first or second).

If the first rotating direction is decided then de-energizing a first locking means (5a) and allowing the _f first locking means (5a) towards the first rotating direction and energizing the first locking means at moved state or position (If we consider crawling action, one movement is done here). For further performing angular movement, de-energizing the second locking means (5b) followed by each 170 energizing/de-energizing action of first locking means (5a) thereby first and second turning means . (6a&6b), rotatable supporting means (1), supporting means (8) correspondingly allow the angular movement for moving the nacelle towards the favourable wind/desired wind direction. The above said similar action to be performed for second rotating direction but second locking means (5b) de-energized initially.

ADVANTAGE OF THE INVENTION

1. The yaw drive of the present invention eliminates the need of large gear assembly.

2. The yaw drive replaces large bearing to two smaller bearing.

3. The simultaneous electromagnetic engagement of locking means like crawling action provides better turning control to achieve yaw action.

4. The free movement of turn table/rotatable supporting means eliminates the need of separate yaw motor.