GB2447561A

GB2447561A - A wind turbine having cyclically controlled blades

Info

Publication number: GB2447561A
Application number: GB0804799A
Authority: GB
Inventors: Pertti Tommila
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-03-15
Filing date: 2008-03-14
Publication date: 2008-09-17
Also published as: DE202008003560U1; FIU20070107U0; DK200800047U3; FI7627U1; GB0804799D0

Abstract

A vertical axis wind turbine 1 comprises at least three blades / vanes 5 rotatably mounted onto a rotor, each blade 5 having a coupling mechanism 6 to control the position of the blade relative to the rotor, the coupling mechanism able to align each blade parallel to the direction of the wind T when the blade is moving against the direction of the wind so as to minimize air resistance. The cyclic control of the wind motor may be achieved either by servo motors (part 8, fig.3), or electromagnetic switches 7 which lock and release the blades at different positions of rotor rotation. Ideally, the electromagnetic switches (eg., solenoids) are located within shafts 6 of each blade, and preferably inside both ends of the shaft 6. Preferably the servos / switches position the blades depending on the direction of the wind, which is indicated by sensors.

Description

I

ROTOR FOR WIND POWER PLANT

1] The invention relates to a rotor for a wind power plant, the ro-tor comprising a frame rotating about a vertical axle and at least three rotor vanes attached to the frame and installed rotationally about a vertical axle ar-ranged vertically relative to the frame.

2] Different rotor solutions for wind power plants are disclosed in publication GB 2000233, for example. Herein, the vanes are locked non-rotationally relative to the frame by using mechanical delimiters, within whose limits a vane is able to rotate only at a given angle relative to the frame.

3] The problem herein is that the position of the vanes at the fi-nal stage of a cycle, i.e. when they approach the turning point on the side of the wind, is such that it resists rotation.

4] The object of the present invention is to provide a rotor solu-tion that achieves a minimal resistance of the vanes as they move against the wind and, correspondingly, a maximal advantage as the wind pushes them downwind. The rotor according to the invention is characterized in that it com-prises at least one coupling member per each vane for coupling the vane at a desired angle relative to the frame of the rotor in such a manner that the force generated by the wind in the vane rotates the rotor and, correspondingly, as the vane moves against the direction of movement of the wind, for setting the vane substantially in the direction of the direction of movement of the wind for minimizing air resistance.

5] An essential idea of the invention is to arrange coupling members between the rotor and the vanes for releasing the vane to rotate freely when it faces away from the wind relative to the rotor axle, whereby it, when moving upwind, settles In a position that minimally resists the wind or for turning the vane in the direction of the wind. Furthermore, it is essential to an embodiment that when the vane is at the rotor edge facing the side of the wind, it is locked relative to the rotor in a manner preventing it from rotating freely.

Thereby, as the rotor rotates, it turns in such a manner that the wind starts to act on its side surface, thus rotating the rotor by means of the vane. According to an embodiment of the invention, an electromagnetic switch is used as the locking member, by means of which the vane can be locked in the desired po-sition relative to the frame when the vane is at the rotor edge facing the side of the wind and, correspondingly, released simply and reliably on the opposite side. According to another embodiment of the invention, a motor controlled by a servomechanism serves as the coupling member between the rotor and the vane, allowing the vane to be turned in the desired angle relative to the rotor and, correspondingly, allowing the vane to be released to rotate freely or to be positioned in the direction of the wind. This being so, as the rotor rotates and the vane approaches the point of the rotor closest to the wind side, the vane may be turned in an inclined position relative to the vane in such a manner that the wind, when acting on the vane, pushes the vane and thus the rotor in its direction of rotation. Furthermore, as the rotor rotates, the vane may always be adjusted as efficiently as possible to act on the rotation of the rotor and, corre-spondingly, as the vane arrives at the rotor side facing away from the wind, it can be inclined relative to the rotor in such a manner that, as the wind acts on the vane, it achieves a transverse force that pushes the rotor in its direction of rotation. Thus, the angle of action of the vane can be rendered significantly larger than 1800 and, at the same time, a maximally high effect is achieved from the wind.

BRIEF DESCRIPTION OF THE FIGURES

6] The invention is described in more detail In the accompany-ing figures, in which Figure 1 schematically shows a side view of a rotor, Figure 2 schematically shows a rotor in section along line A -A of Figure 1, Figure 3 schematically shows a side view of a rotor according to an-other embodiment, and Figure 4 schematically shows a rotor according to another embodi-ment in section along line B -B of Figure 3.

7] Figure 1 schematically shows a side view of a rotor accord-ing to the invention.

8] A frame 1 a of a rotor I stands supported by a base 2 and is rotationally installed relative thereto by means of an axle 3. The axle 3 is cou-pled in a manner known per se to a generator, not shown, Installed in the base 2 for generating electric power.

9] The rotor 1 frame I a is provided with horizontal supporting arms 4 attached to the rotor axle 3, which are shown herein by way of example in the form of a lattice in connection with Figure 2. Rotor vanes 5 are rotation-ally attached to the supporting arms 4 by means of axles 6. The axles 6 are mounted on bearings in the supporting arms 4 at both ends of the vane 5 in a manner allowing the vane 5 to easily rotate relative to the supporting arms 4.

The vane axle 6 Is preferably tubular, allowing a coupling member 7 to be In-stalled inside thereof, which in this embodiment is an electromagnetic switch.

The coupling member 7 allows the vane 5 to be supported non-rotationally relative to the supporting arms 4 and, consequently, the rotor I frame I a when the intent is for the vane 5 to receive wind for rotating the rotor I. 10010] Locking takes place when the vane is in its approximately ex-treme position relative to the rotor axle 3 on the side of the wind. This being so, when it turns with the rotor 1, it settles transversely relative to the direction of the wind, and the wind acts on its surface, thus rotating the rotor. Similarly, when the vane 5 is on the opposite side of the rotor 1, i.e. faces away from the wind, its locking is released and it settles in the direction of the wind. In this position, the resistance generated thereby relative to the wind is at Its mini-mum. In order for the vane 5 to settle as well as possible according to the wind when being free, its axle has to be asymmetric relative to the vane 5 in the wider direction of the vane. In this case, one edge of the vane always settles to face the wind when the vane is free. The coupling members 7 are preferably arranged at both ends of the vane 5. The coupling members 7 may be installed inside the axle tube 6 of the vane 5, whereby they lock the axles from inside.

They may naturally also be installed in the arms 4, whereby they lock the axles from outside or at the ends.

1] Figure 2 shows the rotor in section along line A -A of Figure I. It shows the operation of the rotor vanes by way of example when the rotor rotates. When the wind blows in the direction of arrow T, the left-hand vane 5 is locked with the electromagnetic coupling member 7 substantially in the direction of the supporting arm 4, whereby the wind starts to act on its surface as the rotor rotates and makes the rotor rotate in the direction of arrow P. The lowermost vane in the figure, i.e. the vane furthest away from the wind, is re- leased from the locking, allowing it to settle, when the rotor 1 continues to ro- tate, in the direction of the wind, i.e. in a position where it causes as little resis-tance as possible to the rotation of the rotor. From its lowermost position, the vane may turn freely in the direction of propagation of the rotor relative to the supporting arms 4. The uppermost vane in Figure 2, i.e. the one closest to the side of the wind, is locked at said point substantially in the direction of the sup- porting arm 4, whereby when it rotates, the wind starts to act on it, thus gener-ating a force that rotates the rotor.

[00121 For coupling the vanes at the right point, the equipment must naturally comprise sensors and control members for controlling the coupling and the releasing. Accordingly, the equipment comprises a wind direction sen-sor indicating the approach direction of the wind. This direction is the one in which the vane is coupled non-rotary or, similarly, according to which the angle of the vane is adjusted. Correspondingly, the opposite side of the rotor is the one where the vane is disconnected or adjusted in the direction of the wind.

Furthermore, the equipment implemented with coupling members comprises sensors for indicating the arrival of a vane at a coupling point and, correspond- ingly, the arrival of a vane at a releasing point, whereby the coupling and re- leasing of the vanes can be controlled by means of these and the wind direc-tion sensor. In principle, it is sufficient to use, as the wind direction sensor, a control unit that rotates in accordance with the wind direction and comprises coupling and releasing sensors rotating along with it. In this case, the coupling of the wind-side vane and, correspondingly, the release of the vane arriving at the opposite side, always take place correctly relative to the wind direction.

3] Figures 3 and 4 show another embodiment of the invention with the rotor in a side view and, correspondingly, in section along line B -B denoted in Figure 3 and seen in the direction of the axle.

4] Instead of a mere locking mechanism, this embodiment util-izes motors 8 controlled electrically between the rotor I and the vanes 5 by means of servomechanisms and enabling the arrangement of the position of the vanes relative to the rotor I in the desired manner. The motors 8 are lo-cated between the rotor arms 4 and the vanes 5 in a manner allowing the vanes 5 to rotate relative to the rotor 1 around the axle 6 rotated by the servos 8.

5] Figure 3 shows a solution illustrating how the motors 8 are located between the supporting arms 4 and the vanes 5. Such motors 8 and the structure and function of the servomechanisms associated therewith are generally known per se, and therefore need not be explained more specifically in detail. In principle, servomechanisms and the motors controlled thereby function according to signals generated by different controllers and sensors in such a manner that they rotate their object, in this case the rotor vane 5, around its axle, on the basis of data indicated by the controllers and the sen-sors in accordance with sensor instructions to the controller equipment.

10016] Figure 4 shows by way of example how the vanes 5 can be controlled taking into account the wind direction and the capacity attainable in the rotor by means of the vanes. As Figure 4 shows, the vane on the side of the wind, i.e. in the case of Figure 4, the uppermost vane in the figure, is in-clined by angle a relative to the wind direction B by means of the servo. This being so, when the wind blows at the surface of the vane 5, it generates a force that rotates the rotor I in the direction of arrow P. The vane angle a may be adjusted according to the rotation of the rotor I in such a manner that the magnitude of the force generated In the vane by the action of the wind is as suitable as possible as regards the efficiency of the rotation of the rotor. Ac-cordingly, by way of example, the leftmost vane shown in Figure 4 is at said point substantially perpendicularly against the wind direction T. [0017] Figure 4 shows correspondingly, how the lowermost vane 5 in the figure is inclined by angle ( relative to the direction of the wind T, whereby the wind generates a transverse force therein, i.e. a force acting to the right in the figure, and thus also rotates the rotor 1 by means of the force acting on this vane. Angles a and I depend on the structure of the vanes and, naturally, on the location of the vanes on the circumference of rotation. The vane may be suitably inclined before its arrival at the uppermost vane position accordIng to Figure 4 and, correspondingly, the lowermost vane may be at an angle relative to the rotor signfficantly past the lowermost position according to Figure 4, allowing the influence of the vane on the rotation of the rotor to be widened as an angle of rotation significantly exceeding 1800.

[00181 When the rotor rotates in direction B and the lowermost vane arrives at a suitable position on the right-hand side of the point indicated in Figure 4, the vane may be either released from servo control or It may be ro-tated by means of the servo completely into the direction of the wind and kept therein as the rotor rotates until the vane arrives at a suitable point before the extreme position of the rotor on the side of the wind. When arriving at this point, the rotor is either coupled to be rotated by a servo-controlled motor or, when already being rotated by a servo-controlled motor, rotated to the desired angle relative to the rotor supporting arms 4 in a manner generating the push force required for rotating the rotor from the wind.

9] As the solution provided with mere coupling members, the equipment of this embodiment, too, must naturally comprise a sensor and con-trol members, under the control of which the rotation of the vane by means of the servo-controlled motor and possibly the decoupling from the servo control and the coupling back to the servo control take place. In this embodiment, too, a wind direction indicator is required and means are required for the control apparatus, such as a microprocessor or a control unit implemented in other manners, which attends to the servo control and, by means thereof, the rota-tion of the vanes in a manner suitable to the operation. Accordingly, the equipment implemented with servos also comprises sensors indicating when a vane is in a position where its angle has to be adjusted for accomplishing a rotating force and, similarly, set the vane substantially in the direction of the wind for the duration of upwind movement. Different sensors and control units belong to general adjustment and control technique and are generally known to persons skilled in the art. Accordingly, they need not be explained in any greater detail.

0] In the above description and in the figures, the invention Is described by way of example only and is not restricted thereto, but may be ap- plied within the scope of the attached claims. These embodiments are sche-matically shown to comprise four vanes, but fewer or more vanes may be used in a rotor; however, three vanes at minimum in order to achieve a sufficient rotating force. A suitable choice of width and number of vanes provides a rela-tively large area of influence of the vanes relative to the wind on one side of the rotor, but, on the opposite side, the vanes are in a position allowing them to rotate freely into a position causing minimum resistance.

Claims

1. A rotor for a wind power plant, the rotor comprising a frame (Ia) rotating about a vertical axle and at least three vanes (5) attached to the frame (I a) and installed rotationally about a vertical axle arranged vertically relative to the frame, c h a r a c t e r I z e d in that it comprises at least one coupling member (7; 8) per each vane (5) for coupling the vane (5) at a desired angle relative to the frame (Ia) of the rotor (I) in such a manner that the force gener-ated by the wind in the vane (5) rotates the rotor and, correspondingly, as the vane (5) moves against the direction of movement (T) of the wind, for setting the vane substantially In the direction of the direction of movement (T) of the wind for minimizing air resistance.

2. A rotor as claimed in claim 1, characterized in that elec-tromagnetic switches are used as the coupling members (7), which couple the vane (5) non-rotary when it is located at the edge of the rotor (1) on the side of the wind and, correspondingly, release it for rotation when it is located at the edge of the rotor (I) facing away from the wind.

3. A rotor as claimed in daim 2, c h a r a c t e r I z e d in that the electromagnetic switches (7) are installed inside the axles of rotation of the vanes (5).

4.Arotorasclalmedinclaim2or3,charaCteriZed inthatthe electromagnetic switches (7) are installed in both ends of the axles of rotation of the vanes (5).

5.Arotorasclaimedinciaimi,characteflZed:nthatmotors controlled by a servomechanism are used as the coupling members (8), the motors being installed to rotate the vanes (5) according to the direction (T) of the wind into a suitable angle (a; I) relative to the rotor (I).

6.Arotorasclaimedinclaim5,CharaCterized inthatthe servomechanism is arranged to control the motors to rotate the vanes (5), as they approach the position closest to the side of the wind when the rotor ro- tates, into such an angle (a) that the wind generates, in the vane, a force turn-ing the rotor (I) in the direction of rotation (P).

7. A rotor as claimed in claim 5 or 6, c h a r a c t e r i z e d in that the servomechanism is arranged to control the motors to rotate the vanes (5), as they approach the position of the rotor facing away from the wind, into such an angle () that the wind generates, in the vane, a force turning the rotor (I) in the direction of rotation (P).

8. A rotor as claimed in any one of claims 5 to 7, character-I z e d in that the servomechanism is arranged to control the motors to rotate the vanes (5), when they pass the position of the rotor facing away from the wind, into such an angle (li) that the wind generates, in the vane, a force turn-ing the rotor (1) in the direction of rotation (P) still after the position facing away from the wind.