EP2132436A2

EP2132436A2 - Rotor device, wind turbine and method

Info

Publication number: EP2132436A2
Application number: EP08723846A
Authority: EP
Inventors: Edwin Aronds
Original assignee: Edwin Aronds
Current assignee: DE KNAITER BEHEER B.V.
Priority date: 2007-03-07
Filing date: 2008-03-07
Publication date: 2009-12-16
Also published as: WO2008108637A2; NL1033514C2; WO2008108637A3

Abstract

The present invention relates to a rotor device (2) for -use in the production of wind energy, comprising: - at least one rotor shaft (6) which can be arranged substantially transversely of the wind during use, - at least two rotor blades (3,4,5) which are coupled to the rotor shaft (6) and which are arranged such that, during use, at least one rotor blade (3,4,5) moves substantially in the direction of the wind and at least one rotor blade (3,4,5) moves substantially against the direction of the wind, and - a first wind deflector (11,35) which can be arranged such that during use it deflects away from the rotor blades wind which slows down a rotor blade (3,4,5). The present invention also comprises a wind turbine (1) comprising such a rotor device.

Description

Rotor device, wind turbine and method

The present invention relates to a rotor device for use in the production of wind energy. The present in- vention further relates to a wind turbine comprising such a rotor device according to the present invention for use in the production of wind energy. The present invention further relates to a method in respect of such a rotor and/or wind turbine. It is known to produce wind energy for the use thereof. Wind turbines of many types and sizes are used for this purpose. It is for instance possible to use wind turbines for transmitting wind energy in the form of kinetic energy. It is further possible to generate electric- al energy by applying wind energy. A variety of types of wind turbine are known for this purpose. Examples hereof include wind turbines with a shaft arranged in the wind direction and wind turbines with a shaft arranged perpendicularly of the wind direction. Examples of this latter are the Savonius rotor and the Darrieus rotor.

An advantage of such rotors is that they function with any wind direction directed perpendicularly of the shaft. A significant drawback of wind turbines with a rotor shaft in the longitudinal direction of the wind is that they can only be exposed to the wind at determined wind speeds in order to prevent damage thereto. The wind turbines with the rotor shaft directed perpendicularly of the wind do not have this drawback. The wind turbines with the rotor shaft directed vertically of the wind do however have a further drawback, namely that they only have a limited performance because of the principle of the difference in resistance between the driven rotor blades and the return blades. In order to obviate or at least limit this drawback and to provide the possibility of an improved performance, the present invention provides a rotor device for use in the production of wind energy, comprising: - at least one rotor shaft which can be arranged substantially transversely of the wind during use,

- at least two rotor blades which are coupled to the rotor shaft and which are arranged such that, during use, at least one rotor blade moves substantially in the direction of the wind and at least one rotor blade moves substantially against the direction of the wind, and

- a first wind deflector which can be arranged such that during use it deflects away from the rotor blades wind which slows down a rotor blade. By applying the wind deflector a significant resistance encountered by a standard rotor device with rotor shaft disposable transversely of the wind is eliminated or at least limited. The principle of for instance the Savo- nius rotor is that the rotor blades rotate due to a dif- ference in resistance between the blades co-rotating with the direction of the wind and the blades rotating against the direction of the wind. The present invention is based on the insight of further reducing the resistance of the blades rotating against the direction of the wind relative to the resistance of the blades rotating in the direction of the wind. The solution comprises of the wind deflector decreasing the wind pressure on the returning rotors (rotating against the wind) .

In a first preferred embodiment the first wind deflector in the rotor device comprises a wind-separating form, such as a substantially V-shape, which shields the front side of the rotor in the wind direction on the side where the rotor blades rotate against the wind direction. An advantage of such a wind-separating deflector is that a part of the wind can be directed to the part of the rotor rotating away from the wind, or the wind-catching part, while the other part is shielded from the wind. The wind deflector in the rotor device more preferably has a width which in front view, in the wind direction, covers more than half the rotor width, preferably covers more than a full rotor width, and which is preferably arranged such that substantially the whole wind- catching side of the rotor is open in the direction of the wind.

It hereby becomes possible to largely shield the side of the rotor rotating against the wind from the wind and also to shield turbulence occurring on this side from the wind, whereby the braking action of this turbulence is obviated.

The device more preferably comprises substantially horizontal separating elements for separating air flowing through the rotor at different heights. This measure is also effective in preventing turbulence, reducing turbulence and/or reducing the braking action of turbulence.

In a further preferred embodiment the rotor device comprises a second wind deflector which is arranged such that during use it deflects in the direction of the rotor blades wind which accelerates a rotor blade. The wind pressure on the driving rotor blades (co-displacing with the wind) is hereby increased, whereby the efficiency of the rotor can be improved. The combination of the first and second wind deflectors provides an increased wind pressure on the frontal view surface of the rotor blades as seen from the direction from which the wind originates. A further preferred embodiment comprises comprising rotation means for mounting the first and/or second wind deflector for rotation about the rotor axis. It hereby becomes possible for instance to hold the first and/or second wind deflector directed into the wind such that the wind would press as well as possible against the driven part of the rotor blade or the rotor blades.

In a further preferred embodiment the rotor device comprises a deflector orientation unit, preferably com- prising a wind vane, for bringing and/or holding the first and/or second wind deflector in a desirable orientation relative to the wind and/or the rotor shaft. In addition to using said wind vane, this is also possible by means of for instance a motor-driven deflector orientation unit, which for instance receives wind direction information from a wind direction meter. Information from the rotor device itself can optionally be used for the purpose of measuring the wind direction.

The first and/or second wind deflector preferably comprises a casing part preferably having a substantially cylindrical form. The cylindrical form is closely associated with a Savonius rotor. It is for instance likewise possible to apply a casing part with a spherical form, this being associated with a Darrieus rotor. Said cylin- drical form will of course extend over only a part of the periphery of the rotor.

Using an inlet guide member the wind deflector, in a further preferred embodiment, the wind can be guided towards the inlet opening on the side substantially directed toward the wind during use. The inlet guide member can be a determined form of the front side of the first wind deflector. It may however also comprise an additional member such as a wind guiding fin. Such a wind guide fin is ap- plied for the purpose of separating the wind some distance from the rotor blades. A part of the wind will here be guided round the outside of the rotor, thereby effectively reducing the resistance of the returning rotor blades. On the other hand, a part of the wind will be guided in the direction of the driven rotor blades, effectively causing the pressure thereon to become greater. The precise form of the inlet guide member and/or the wind guide fin can be determined in detail within the concept of the present in- vention by the skilled person during the design of specific embodiments according to the present invention.

In a further preferred embodiment the first and/or second wind deflector comprises an outlet guide member substantially on the side remote from the wind during use. Using such an outlet guide member the airflow flowing out or flowing away can be guided such that resistance- increasing turbulences can be prevented or reduced. An optimal mixing of the airflows flowing round the rotor device and the air flowing therethrough can also be realized using the outlet guide member.

A further measure which can reduce the resistance of the return rotor blades is to provide lateral air outflow openings. These can for instance be arranged in the cylindrical part of the first wind deflector. An advantage of such an air outflow opening is that the braking pressure on the return blades can be reduced.

These air outflow openings are more preferably provided with an upwind shield. An advantage hereof is that the outflowing air is not obstructed by the air flow- ing past, or less so.

In a further preferred embodiment the rotor device comprises a plurality of stages of rotor blades, wherein the rotor blades can be disposable per stage in a differ- ent mutual orientation relative to the rotor shaft. An advantage hereof is that a maximum continuity in the wind capture can be achieved with a minimum number of blades per stage. If for instance two blades lie opposite each other per stage, a wind capture is still possible equivalent to that with four blades per stage. The driving hereby becomes more uniform.

A further aspect of the present invention relates to a wind turbine comprising a rotor device according to the present invention, wherein the wind turbine comprises a dynamo or generator for converting kinetic energy into electrical energy and/or a transmission mechanism for transmitting kinetic energy to an apparatus or system to be driven. Such a wind turbine has advantages which are also present in the rotor device according to the present invention as specified in the foregoing.

A further aspect of the present invention relates to a method for using the device as specified in the foregoing, wherein the method comprises steps for placing and connecting and/or steps for take-off of the produced wind energy.

Further advantages, features and details of the present invention will be described hereinbelow on the basis of preferred embodiments with reference to the accom- panying figures, in which

- Fig. 1 is a schematic cross-section of a first preferred embodiment according to the present invention with three rotor blades per stage,

- Fig. 2 is a perspective view of a further embo- diment with two rotor blades and two stages,

- Fig. 3 is a schematic perspective view of a further preferred embodiment according to the present invention, - Fig. 4 is a schematic top view of the embodiment according to Fig. 3.

A preferred embodiment according to the present invention (fig. 1) relates to a wind turbine 1. The wind turbine is shown in cross-section. The wind turbine is a Savonius type of wind turbine with a rotor 2. Rotor 2 comprises three rotor blades 3,4,5. The three rotor blades are mounted on a rotor shaft 6. Although three rotor blades are shown in this preferred embodiment, configura- tions are also possible with two, four, five or six rotor blades, and possibly more.

As is usual in a Savonius type wind turbine, the rotor blades rotate. The rotor blades rotate within a substantially cylindrical space, which is designated by means of the broken circular line which specifies the ends of the rotor blades.

Central shaft 6 will rotate due to driving of the rotor blades and a device or a dynamo for generating electrical energy can be driven by means of this kinetic ener- gy. These components are not shown per se. A transmission (not shown) can be provided for the purpose of adjusting the rotation speed of the shaft to a possible device or dynamo to be driven.

The operation of the Savonius wind turbine is based on the difference in resistance between the rotor blades co-displacing with the wind and the rotor blades rotating against the wind. Different types of Savonius rotor are known, including rotors with two separate half- spheres as rotor blade and rotors with two curved blades situated opposite each other. A known optimization in Savonius rotors is that the wind can be guided between the blades so that the blades moving against the wind gain some additional push from the wind which is first captured in the blades co-displacing with the wind.

The simplicity of the known Savonius rotor is also a source of its limitations. The produced energy is for instance limited to the difference in resistance of the driven rotor blades relative to the returning rotor blades. In order to increase this difference it is an object of the present invention to reduce the resistance on the returning rotor blades. A further object is to rela- tively increase the resistance on the driven rotor blades.

Under the influence of the wind in the direction of arrows w the rotor blades rotate in the direction of arrow R. The rotor blade 4 moving against the wind is under the influence of the same wind as the rotor blades 3,5 co-displacing with the wind. In the case there are two rotor blades, the driven rotor blade will be in symmetrical position relative to rotor blade 4 relative to shaft 6.

Wind deflector 11 serves to obstruct the wind against which rotor blade 4 has to move. In its simplest form wind deflector 12 is a roughly semi-round cylinder, this being shown in the figure by wall parts 12 and 15. These wall parts serve to shield rotor blade 4, or at least the part of the space of the rotor where the rotor blade moves against the wind. In this simplest embodiment with only wall parts 12 and 15, deflector 21 is not present either. The wind is therefore deflected round wind deflector wall 12,15 and can further move freely round wind turbine 1. Alternative embodiments further comprise the respective parts 13,19,17,18,20,16,21, as will be de- scribed hereinbelow.

In a further embodiment the wind deflector 11 comprising wall parts 12 and 15 is augmented with a fin 13 with a leading edge 14. This fin has a form such that as much wind as possible is urged in a direction suitable for the driving of the rotor in the direction of the rotor space. In the figure this fin is shown with a form which is spherical toward the front side. In an alternative such a form is straight or concave. A further object of such a fin is to limit turbulence on the front side of the rotor. The front side is understood to mean the side from which the wind comes.

In a further preferred embodiment deflector 11 is provided with a wind guide member 16 on the rear side thereof. The rear side is understood to mean the side toward which the wind blows. This wind guide member or spoiler 16 serves to limit turbulence where the wind blowing under the deflector rejoins the wind driving the rotor blades. The form of this spoiler can also depend on the conditions and can be further specified within the scope of the present invention by the skilled person.

In a further embodiment cylinder wall 12,15 is provided with respective openings 17,18 for allowing out- flow therethrough of air driven by the returning blades, as shown here in figure 1 by means of blade 4. In order to allow an easy passage for the air flowing out through these openings 17,18, flaps 19,20 are further provided which shield this outflow opening against the wind flowing past. It is also advantageous if an underpressure were to occur behind flaps 19,20 due to wind flowing past, whereby driving of the returning rotor as shown in the position of rotor 4 is stimulated in that air is drawn out of the left-hand space of the rotor space by this underpressure. The form of flaps 19,20 can herein also be determined experimentally subject to conditions by the skilled person within the scope of the present invention. A further embodiment comprises a second deflector 21 on the other side of deflector 11 of the rotor space indicated by means of the broken circular line, this deflector being intended for the purpose of capturing the wind in order to drive the rotor blades driven by the wind on their high-resistance side. Any form of this deflector can be determined subject to the conditions, such as the shape of the rotor blade, frequently occurring wind types and speeds and the like. The shape on the front side close to edge 22 serves to minimize turbulence and to maximize the effect of the driving of the rotor blades. A shape can also be provided on the rear side of this deflector 21 which can be determined by the skilled person subject to the parameters of the embodiment within the scope of the present invention.

Wind turbine 1 is preferably rotatable so that it can be directed into the wind. Because the rotor has the same operation per se in any direction, it suffices that the deflectors are rotatable relative to the wind. In ad- dition, the deflectors are optionally rotatable to some extent relative to each other in order to provide an optimal operation in any wind direction. The form of the inlet and outlet 13,16,22 of the deflectors is for instance also adjustable here subject to for instance the wind speed.

For the purpose of directing the deflectors the spoiler 16 can for instance have a determined length such that it obtains a steering action. Separately of these deflectors it is however also possible to couple a vane thereto such that this additional vane (not shown) can provide for a correct orientation relative to the wind direction. It is further possible to provide a wind direction meter with a control mechanism and a drive, for in- stance in the form of an electric motor. A number of wind turbines can for instance be oriented here in the correct direction on the basis of data from one wind direction meter. Fig. 2 shows a perspective view of an embodiment comprising two stages, each with two blades. The arrangement of the wind deflectors is here substantially the same as that of the above described embodiment. The stages are bounded and separated by means of substantially round plates 31,32,33. As seen in top view, rotor blades 23 and 24 of the upper stage are offset/rotated 90 degrees relative to rotor blades 25 and 27 of the lower stage.

An advantage of the present invention is that it makes the Savonius rotor intrinsically more efficient at all wind speeds in that the resistance of the driven rotor blades is increased relative to the rotor blades moving against the wind. A wind turbine with for instance a Savonius rotor hereby becomes applicable or cost-effective under more varied conditions. Fig. 3 and Fig. 4 show a further preferred embodiment. The rotor blades are not shown for the sake of simplicity of the figure. These are similar to the rotor blades of the above described embodiments. This wind turbine 29 comprises a rotor with two stages, which are mu- tually separated by means of a partition wall, and is bounded on the top side by an upper wall 30 and is bounded on the underside by a lower wall 32. These walls have the function of preventing turbulence and preventing energy loss on the top and bottom sides. The rotor is rotatable about a central axis, and also the components which are static relative to the wind direction, including deflector 35, frame construction 40 and wind vane 41, are rotatable around this central axis 34. Deflector part 35 of the device is preferably embodied as a structural unit together with this frame 40 and the wind vane.

Frame 40 here connects the wind vane and deflector 35. The deflector is preferably embodied in simple manner as two plates 36,37, such as metal or plastic plates. The plates are preferably constructed from a plate with a bend line 38. The frame preferably comprises a T-profile 40 for a simple, strong construction, although the skilled person will be able to devise equivalent alternatives for the construction of a frame within his general professional knowledge in the field. The frame is connected to rotor shaft 6.

The wind deflector preferably provides a protec- tion from the wind to the part of the rotor moving against the wind, and is preferably wider here than half the rotor. Since the front side of the wind-capturing part of the rotor is free for incident wind, the deflector can protrude on the side of the rotor rotating against the wind. The deflector herein provides a wind-free zone in which the rotor can move in this direction without wind resistance. When sufficiently wide, the deflector can even prevent the braking action of the wind on turbulence in the created windless zone. The wind deflector can herein extend further rearward than the front side of the rotor. In other words, the side of plate 37 can extend further to the rear.

The present invention has been described in the foregoing on the basis of several preferred embodiments. Different aspects of different embodiments are deemed described in combination with each other, wherein all combinations which can be made by a skilled person on the basis of this document must be included. These preferred embodi- ments are not limitative for the scope of protection of this text. The rights sought are defined in the appended claims.

Claims

1. Rotor device for use in the production of wind energy, comprising: - at least one rotor axis which can be arranged substantially transversely of the wind during use,

- at least two rotor blades which are coupled to the rotor axis and which are arranged such that, during use, at least one rotor blade moves substantially in the direction of the wind and at least one rotor blade moves substantially against the direction of the wind, and

- a first wind deflector which can be arranged such that during use it deflects away from the rotor blades wind which slows down a rotor blade.

2. Rotor device as claimed in claim 1, wherein the first wind deflector has a wind-separating form, such as a substantially V-shape, which shields the front side of the rotor in the wind direction on the side where the rotor blades rotate against the wind direction.

3. Rotor device as claimed in one or more of the foregoing claims, wherein the wind deflector has a width which in front view, in the wind direction, covers more than half the rotor width, preferably covers more than a full rotor width, and which is preferably arranged such that substantially the whole wind-catching side of the rotor is open in the direction of the wind.

4. Rotor device as claimed in one or more of the foregoing claims, comprising substantially horizontal separating elements for separating air flowing through the rotor at different heights.

5. Rotor device as claimed in one or more of the foregoing claims, comprising a deflector orientation unit, preferably comprising a wind vane, for bringing and/or holding the first and/or second wind deflector in a desirable orientation relative to the wind and/or the rotor axis .

6. Rotor device as claimed in one or more of the foregoing claims, comprising a plurality of stages of rotor blades, wherein the rotor blades can be disposable per stage in a different mutual orientation relative to the rotor axis.

7. Rotor device as claimed in one or more of the foregoing claims, comprising a second wind deflector which can be arranged such that during use it deflects in the direction of the rotor blades wind which accelerates a rotor blade.

8. Rotor device as claimed in one or more of the foregoing claims, comprising rotation means for mounting the first and/or second wind deflector for rotation about the rotor axis.

9. Rotor device as claimed in one or more of the foregoing claims, wherein the first and/or second wind deflector comprises a casing part preferably having a substantially cylindrical form.

10. Rotor device as claimed in one or more of the foregoing claims, wherein the first and/or second wind deflector comprises an inlet guide member on the side substantially directed toward the wind during use.

11. Rotor device as claimed in claim 10, wherein the inlet guide member of the first wind deflector comprises a wind guide fin for separating the wind some distance from the rotor blades.

12. Rotor device as claimed in one or more of the foregoing claims, wherein the first and/or second wind deflector comprises an outlet guide member substantially on the side remote from the wind during use.

13. Rotor device as claimed in one or more of the foregoing claims, wherein the first wind deflector comprises lateral air outflow openings.

14. Rotor device as claimed in claim 13, wherein the air outflow openings are provided with an upwind shield.

15. Rotor device as claimed in one or more of the foregoing claims, wherein the rotor axis is situated in a substantially vertical orientation in the position of use.

16. Wind turbine comprising a rotor device as claimed in one or more of the foregoing claims, comprising a dynamo or generator for converting kinetic energy into electrical energy and/or a transmission mechanism for transmitting kinetic energy to an apparatus or system to be driven.

17. Method for using a device as claimed in one or more of the foregoing claims, comprising steps for placing and connecting and/or steps for take-off of the produced wind energy.