WO2019073175A1

WO2019073175A1 - Vertical wind turbine with pivoting blades

Info

Publication number: WO2019073175A1
Application number: PCT/FR2018/052515
Authority: WO
Inventors: Sébastien CUSSAC; Pascal EPINEAU; Christophe Leveque
Original assignee: Collaborative Energy
Priority date: 2017-10-11
Filing date: 2018-10-10
Publication date: 2019-04-18
Also published as: FR3072134B1; FR3072134A1

Abstract

The invention relates to a wind turbine (1), comprising blades (20, 20', 20f, 20f', 20a) turning about a central axis of rotation (Z), the central axis of rotation being intended to be orientated vertically, the wind turbine comprising a rigid frame (2), comprising at least one arm (10) holding the blades, and extending transverse to the central axis of rotation (Z), each blade comprising a leading edge (21) and a trailing edge (22), such that depending on the direction of rotation of the wind turbine (Ω), the leading edge is arranged in front of the trailing edge, the wind turbine comprising at least two blades (20, 20'), pivoting blades, each pivoting blade being such that: the pivoting blade (20) is connected at a point of the arm, termed the attachment point (15, 15'), the pivoting blade being able to rotate, about the attachment point, along a pivoting axis (W, W); - the pivoting blade (20) is connected to another pivoting blade (20') by a flexible link (23), termed the association link; the wind turbine being characterised in that: each pivoting blade is associated with a point, termed the docking point (25, 25'), situated on the frame, the docking point being closer to the trailing edge (22) than to the leading edge (21); - each pivoting blade is connected to the docking point (25, 25') associated therewith; in such a way as to limit a displacement, with respect to the docking point, of said blade pivoting about the pivoting axis.

Description

Vertical wind turbine with swivel blades Description

TECHNICAL AREA

The technical field of the invention is that of vertical axis wind turbines. PRIOR ART

The use of wind as a source of energy is old, but it is currently experiencing a renewed interest due to the growth in demand for renewable energy. Recently, we have seen the development of wind turbines to produce electricity. These are essentially horizontal wind turbines. However, horizontal axis wind turbines do not align spontaneously with the direction of the wind and must have a dedicated steering mechanism. In addition, in order to be exposed to strong and constant winds, they require an installation several meters high, which poses aesthetic nuisances and makes the installation expensive, as well as the maintenance operations, in particular concerning the orientation mechanism.

Parallel to horizontal axis wind turbines, vertical axis wind turbines have been developed. They have the advantage of being able to be installed near the ground, and to be less expensive than vertical axis wind turbines, and to present a good compromise between the power released and the surface occupied on the ground, typically of the order of 20 W / m ² . In addition, they can operate in light winds, whatever its orientation. Several types of vertical axis wind turbines have been designed:

Savonius-type wind turbines, which have fixed and curved blades, take the form of half-cylinders slightly offset from each other. The blades generally extend from a rotating shaft of the wind turbine. Such wind turbines can operate in a light wind, but their performance is limited when the wind speed increases.

Darrieus type wind turbines, which have fixed blades, each blade being disposed at the end of an arm, perpendicular to the latter. Each arm extends between the axis of rotation of the wind turbine and the blade. Such turbines have a higher efficiency than Savonius wind turbines when the wind is high. However, their start is difficult, especially compared to Savonius type wind turbines.

Panemones with mobile blades, whose blades are arranged at the end of an arm, and, unlike Darrieus type wind turbines, are movable relative to the latter.

The patent application EP0021790 describes a panemone wind turbine, each blade having a leading edge and a trailing edge, each blade being disposed at the end of an arm. Each blade is connected, by its leading edge, to the arm now, and is rotatable relative to to the latter. Each blade also has a link, extending between the trailing edge of said blade and the trailing edges of other blades. The function of the link is to limit the movement of the blade around the arm now. According to this wind turbine, the rotational movements of two opposite blades are symmetrical and synchronous: when a blade pivots at an angle, approaching the central axis of rotation of the wind turbine, the opposite blade pivots simultaneously, according to the same angle, away from the central axis of rotation.

The wind turbine described in the French patent application FR2997736 can be considered as an improvement of the device disclosed in EP0021790. In this wind turbine, the trailing edges of two diametrically opposed blades are connected by a link. The link is deformable, around one or more so-called return means, the latter being movable. This wind turbine is arranged such that when a blade pivots too much with respect to the arm now, the opposite blade tends to limit its spacing, due to the presence of the link between the two blades. When the speed of rotation increases, the configuration of the wind turbine tends to a configuration of Darrieus type, previously mentioned. However, the inventors have found that this wind turbine could still be improved, and in particular by better control of the angular clearance of the blades, particularly at low rotational speeds. They have devised the invention, described hereinafter, for this purpose.

SUMMARY OF THE INVENTION

An object of the invention is a wind turbine, comprising blades configured to rotate about a central axis of rotation in a direction of rotation, the central axis of rotation being intended to be oriented vertically, the wind turbine comprising a rigid frame , the chassis comprising at least one arm holding the blades and extending transversely to the central axis of rotation, each blade having a leading edge and a trailing edge, so that in the direction of rotation, the edge of attack is arranged in front of the trailing edge, the wind turbine comprising at least two blades, said pivoting blades, each pivoting blade being such that:

the pivoting blade is connected to a point of the arm, said point of attachment, the pivoting blade being movable in rotation about the point of attachment, along a pivot axis;

the pivoting blade is connected to another pivoting blade by a link, preferably flexible, said association link;

the wind turbine being characterized in that:

each pivoting blade is associated with a point, called the firing point, located on the chassis, the firing point preferably being closer to the point of attachment than to the central axis of rotation; each pivoting blade is connected to the firing point associated with it; so as to limit a movement, relative to the firing point, of said pivoting blade, around the pivot axis.

The connection between the firing point and the pivoting blade serves to maintain, during the pivoting of the blade around the pivot axis, the trailing edge at a distance, less than a predetermined maximum distance, from the firing point. .

Preferably, the firing point is a fixed point of the frame. Alternatively, it can be mobile with respect to the latter. In the latter case, the displacement of the firing point, relative to the frame, is limited in a range of displacement, extending for example by a distance of less than 5 cm or 10 cm.

Preferably, the firing points, respectively associated with two different pivoting blades, are different.

Preferably, the firing point is closer to the central axis of rotation than is the point of attachment. The points of attachment and firing can also be arranged equidistant from the central axis of rotation.

The distance between the point of attachment and the blade corresponds to a first radius of the wind turbine. Preferably, the firing point is disposed at a distance greater than half the first radius, or even greater than 75% of the first radius, of the central axis of rotation.

According to one embodiment, at least one pivoting blade is connected, at the firing point associated with it, by a return link extending between said firing point and a point, said point of intersection, located on the link of FIG. association connected to said blade.

According to another embodiment, the pivoting blade is connected, at the firing point associated with it, by a return link extending between said firing point and a point, said point of intersection, located on said blade.

Whatever the embodiment, the point of intersection is advantageously closer to the trailing edge than the point of attachment, and / or between the trailing edge and the point of attachment.

Whatever the embodiment, the return link is preferably movable around the firing point, along an axis that can be parallel to the central axis of rotation, or inclined relative thereto. The return link is preferably movable with respect to the firing point according to a ball joint junction.

The association link associated with the pivoting blade extending along a length, between said pivoting blade and the other pivoting blade, the firing point can be disposed at a distance, less than one-fifth of said length, from the trailing edge of said pivoting blade.

The other pivoting blade may be a blade opposite the pivoting blade. The firing point associated with a pivoting blade can be disposed on the arm holding said pivoting blade. It may also be disposed on an arm, said adjacent arm, maintaining an adjacent blade of the pivoting blade.

The attachment point is preferably disposed closer to the leading edge than the trailing edge, and / or between the leading edge and the trailing edge.

The length of the return link is preferably fixed; alternatively, it is variable in a range, for example less than ± 25% or even ± 50%, around a nominal length. The length of the return link, or its nominal length, is preferably less than or at half the distance between the trailing edge of the leading edge.

Preferably, the firing point is closer to the trailing edge than the point of attachment.

Preferably, at least one pivoting blade defines a blade axis, extending between the trailing edge and the leading edge. The pivoting blade has a surface center. The pivoting blade corresponds to a so-called reference position, such that when the blade extends in the reference position, the axis of the blade defines a reference axis, the reference axis being perpendicular to a straight line. extending in a plane perpendicular to the axis of rotation, and connecting the axis of rotation to the surface center of the blade. The deflection of the trailing edge of the blade is then limited so that:

- When the blade tilts closer to the central axis of rotation, the angle between the blade axis and the reference axis is less than a first limit angle;

- When the blade tilts away from the central axis of rotation the angle between the blade axis and the reference axis is less than a second limit angle;

the first limiting angle being greater than the second limiting angle.

The first limiting angle may be less than or equal to 60 ° or 50 ° or even 45 °, and / or the second limiting angle is less than 20 °, or even less than 10 °.

According to one embodiment, the wind turbine comprises:

at least two opposite pivoting blades,

at least two fixed blades, opposite, connected to an arm, and stationary relative to the latter. The wind turbine may comprise 2 pivoting blades, or a number of pivoting blades greater than 2.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and shown in the figures listed below.

FIGURES

Figure 1 shows a first embodiment of the invention. FIGS. 2A, 2B and 2C show different configurations of the blades of the wind turbine, according to the first embodiment, at different speeds of rotation, in constant wind. These figures correspond to values of a speed parameter respectively higher and higher.

FIGS. 3A to 3D illustrate the configurations of the blades of the wind turbine at a low rotational speed, according to four respective angular positions.

FIGS. 4A to 4D illustrate the configurations of the blades of the wind turbine at an average rotational speed, according to the four respective angular positions described with reference to FIGS. 3A to 3D. FIGS. 5A to 5D illustrate the configurations of the blades of the wind turbine at a high speed of rotation, according to the four respective angular positions described with reference to FIGS. 3A to 3D.

Figure 6 shows another embodiment of the invention.

Figure 7 is a photograph of another embodiment.

FIGS. 8A and 8B show wind turbines used in comparative tests, respectively representative of the invention and of the prior art.

Figure 8C shows the comparative test results between a wind turbine as shown in Figure 8A and the wind turbine shown in Figure 8B. FIG. 8D represents an electrical diagram implemented during the comparative tests.

DESCRIPTION OF PARTICULAR EMBODIMENTS

FIG. 1 represents a wind turbine 1 according to a first embodiment of the invention. The wind turbine comprises a frame 2, extending along a vertical axis Z, and of which FIG. 1 represents a transverse view, along a horizontal plane XY. The frame 2 comprises a rigid arm 10. The arm 10 is rotatable about the vertical axis Z, the latter constituting an axis of rotation, said central axis of rotation, of the wind turbine. The term "one" is to be interpreted as meaning "at least one". At a first end 11 of the arm 10 is fixed a blade 20. The blade 20 comprises a leading edge 21 and a trailing edge 22. In a conventional manner, when the wind turbine is operating, the arm 10 follows a rotational movement and the blade 20 is oriented such that, in a direction of rotation Ω, the leading edge 21 is placed in front of the trailing edge 22.

As in the documents cited in connection with the prior art, the blade 20 is pivotable relative to the arm 10. More specifically, the pivoting blade 20 is connected to the first end 11 of the arm 10 at a point, said point d The attachment point 15 is formed in the arm 10, at the first end. In this example, the point of attachment 15 is a fixed point relative to the arm 10. The pivoting blade 20 is rotatable about the point of attachment 15, along a pivot axis W. In this example, the pivoting blade extends parallel to the central axis of rotation Z. The pivot axis W is then parallel to the central axis of rotation Z. It is therefore oriented parallel to the vertical. This condition is not necessary. According to others configurations, the pivot axis W can be inclined relative to the central axis of rotation Z. This is particularly the case when the pivoting blade 20 extends along a plane inclined relative to the vertical.

In this example, the attachment point 15 is located outside the blade, at the leading edge 21. According to a variant, it can be formed in the blade, for example between the leading edge 21 and the trailing edge 22. Whatever the embodiment, the blade pivots about the attachment point 15. Preferably, the attachment point 15 is closer to the leading edge 21 than the trailing edge 22 , and / or between the leading edge 21 and the trailing edge 22.

The wind turbine comprises another pivoting blade 20 ', called the opposite blade, diametrically opposed to the blade 20. In the rest of this description, the term opposite blade designates a diametrically opposed blade, considering an angular tolerance of ± 30 ° or ± 20 ° with respect to the diameter. In this example, the opposite blade 20 'is identical to the blade 20. It is connected to a second end 11' of the arm 10. It comprises a leading edge 21 'and a trailing edge 22'. It is connected, by its leading edge 21 ', to an attachment point 15', the attachment point 15 'being formed at the second end 11'. The opposite blade 20 'is rotatable relative to the point of attachment 15' about a pivot axis W "parallel to the central axis of rotation Z.

The attachment points 15 and 15 'being integral with the arm 10, they are rotatable about the central axis of rotation Z. It is the same pivot axes W and W ".

In other examples, the opposite blade 20 'is obtained, from the pivoting blade 20, by a rotation angle of between 150 ° and 210 ° about the axis of rotation Z, a rotation of 180 ° corresponding in the particular case of a blade strictly diametrically opposed to the pivoting blade 20.

In order to limit the respective angular deflections of the blade 20 and the opposite blade 20 'around their respective pivot axes W and W ", a link 23, said association link, connects the blade 20 to the opposite blade 20' The action of the association link is particularly important during the phases of tacking or jibeing of a blade, when the latter extends parallel to the direction of the wind V. More specifically, to each pivoting blade 20 20 'is associated with a point 28, 28', said point of association, and the association link 23 extends between the respective points of association of the blades between which it extends. a pivoting blade 20 is preferably closer to the trailing edge 22 than the point of attachment 15, and / or between the trailing edge 22 and the attachment point 15.

The association link 23 can be flexible. By flexible means that its shape is not fixed; it evolves according to the position of the blades, associated by the association link, with respect to the direction of the wind V, as well as the speed of rotation around the central axis of rotation Z. The link association 23 may be formed of a flexible material, for example a strap or a rope, or be composed of rigid segments articulated at points of articulation. The rigid segments may be formed by rods. The association link 23 makes it possible to associate at least two blades with one another, the respective angular displacements of the two blades, around their respective pivot axes, thus being rendered dependent on one another. Angular displacement of a blade means the travel around the pivot axis W, W ".

The blade 20 may extend, parallel to the central axis of rotation Z, at a height of between 50 cm and 5 meters, or even 10 or 50 meters or more. The blade can also extend along a plane inclined relative to the central axis of rotation, forming, with respect to the latter, an inclination angle of up to 45 ° or 60 °. The radius of the arm, that is to say the distance between the central axis of rotation Z and the first end 11 (or the second end 11 ') may be between 20 cm and 5 meters, or even 10 meters or more. The length of each blade, that is to say the distance between the leading edge 21 and the trailing edge 22, may be between 10 cm and 5 m or more. The arm 10 is preferably made of a rigid material, for example a metal or a solid plastic material or a composite material. Each blade 20 may be formed of a preferably rigid material, this material being for example a plastic, a composite material or a light metal, for example aluminum, or wood, or a fiber material, for example comprising carbon fibers. It may also be a flexible material, for example a material used in the manufacture of a nautical sail, advantageously stiffened by a rigid or flexible frame.

An important aspect of the invention is that the pivoting blade 20 is associated with a point, called firing point 25, located on the chassis. It is connected to the firing point by a return link 26. Preferably, the firing point 25 is fixed relative to the arm 10 carrying the blade 20. It is preferably fixed relative to the point of attachment 15. The point firing 25 associated with a blade is different from the point of attachment 15 of said blade. While the attachment point 15 is advantageously located closer to the leading edge 21 than the trailing edge 22, and defines the pivot axis W, the firing point 25 is located closer to the trailing edge 22 than the leading edge 21, and contributes to limiting the angular deflection of the blade 20 around the pivot axis W, via the return link 26. The firing point 25 can be movable relative to the frame 2 , but its displacement is then limited in a range of displacement, extending for example on 5 or 10 cm. The firing point 25 is preferably closer to the attachment point 15 than to the central axis of rotation Z. If a first radius of the wind turbine is defined as being the distance between the central axis of rotation Z and the point of attachment 15, the distance between the firing point 25 and the central axis of rotation Z is advantageously greater than half the first radius, or even greater than two-thirds of the first radius, or 75% of the first radius. Ray. The attachment point 15 defines, during a rotation of the wind turbine, a circle, said peripheral circle C, centered on the central axis of rotation Z. The firing point 25 is arranged closer to the peripheral circle C than the central axis of rotation Z.

In the example shown in FIG. 1, the firing point 25 is located on a first auxiliary end 12 of the arm 10. The first auxiliary end 12 is configured such that the pivoting blade 20 extends between the first end 11 and the first auxiliary end 12. Similarly, the firing point 25 ', associated with the opposite pivoting blade 20', is located on a second auxiliary end 12 'of the arm 10. The second auxiliary end 12' is configured such that whereby the opposite pivoting blade 20 'extends between the second end 11' and the second auxiliary end 12 '.

In the example shown in FIG. 1, the return link 26 extends between the firing point 25 and an intersection point 27, situated on the association link 23. The return link 26 can be formed by a rigid or flexible material. It is rigid or flexible. Its length is preferably fixed. In this example, the pivoting blade 20 is connected to the firing point 25:

by a segment 24 of the association link 23, extending between the association point 28 and the intersection point 27;

and by the return link 26, extending between the point of intersection 27 and the firing point 25.

The point of intersection 27 forms a point of articulation of the association link 23. By point of articulation, is meant a point disposed between two adjacent segments of the association link, said segments being articulated around the point of articulation. .

The return link 26 may advantageously be fixed to the firing point 25 by a ball-type junction, allowing a rotation of the return link 26, around the firing point 25, according to several degrees of freedom.

Thus, each pivoting blade 20 is associated with a firing point 25. The respective firing points 25 of two different pivoting blades are distinct. FIG. 1 also shows the firing point 25 'associated with the opposite blade 20', as well as the return link 26 'connecting between the firing point 25' and the trailing edge 22 'of the opposite blade .

Whatever the embodiment, the point of intersection 27 is preferably disposed closer to the trailing edge 22 than the point of attachment 15, and / or between the trailing edge 22 and the point of attachment 15. Its position varies according to the geometry of the blades and the arm holding the blades. It is preferably defined experimentally, or on the basis of numerical simulations.

It is conceivable that, in other configurations, the return link 26 extends directly between the firing point 25 and the blade, the latter being then connected to both the return link 26 and In this case, the return link 26 extends between the firing point and a point of intersection 27, the latter being located on the blade, and preferably between the trailing edge 22 and the point of attachment 15.

The provisions of the firing point 25, the return link 26, and the intersection point 27 are adjusted case by case, depending on the geometry of the frame 2, and in particular the arm 10 carrying the pivoting blade 20. However, Generally speaking, it is preferable that at least one of the following conditions be met:

The firing point 25 associated with a blade is closer to the central axis of rotation Z than is the point of attachment 15 of said blade. In other words, the firing point 25 associated with each pivoting blade being located at a second radius, strictly less than the first radius, of the central axis of rotation. According to a variant, the firing point 25 associated with a blade is located at an equal distance from the central axis of rotation as the point of attachment of said blade: according to this variant, the firing point 25 is disposed on the circle peripheral.

The distance between the intersection point 27 and the central axis Z is variable depending on the speed of rotation and / or the position of the blade 20 relative to the wind direction V.

The distance between the trailing edge 22 and the central axis Z is variable depending on the speed of rotation and / or the position of the blade 20 relative to the wind direction V.

The distance between the firing point 25 and the intersection point 27 is constant, or undergoes a relative variation of ± 25%, or even ± 50% during a rotation. Thus, during a rotation, the point of intersection 27 follows a curved trajectory around the firing point 25.

The return link 26 is rotatable about the firing point 25, along a pivot axis U, said secondary pivot axis, in this example parallel to the central axis of rotation Z, and passing through the firing point 25. .

Considering the direction of rotation Ω, the firing point 25 is located behind the trailing edge 22 of the blade 20 with which it is associated. It is therefore located behind the hooked point 15.

The association link 23 extends between two opposite pivoting blades 20, 20 'along a length; the point of intersection 27 is located at a distance from the trailing edge 22 of less than one-third to one-quarter to one-fifth of said length.

The distance between the trailing edge 22 of the blade 20 and the firing point 25 associated with said blade is less than one fifth, or one quarter, of the length of the association link 23 extending from the blade.

The blade 20 extends between the leading edge 21 and the trailing edge 22, along a length, called blade length. The firing point 25 is located at a distance from the trailing edge 22 less than half or even third of the blade length. The length of the return link is fixed, or is variable within a range of ± 25% or ± 50% around a nominal length. The length, or nominal length, of the return link is preferably less than the blade length, or half the blade length.

- The firing point 25 is closer to the trailing edge 22 than the leading edge 21 of the blade.

FIGS. 2A, 2B and 2C show the effect of the return link 26 on the angular displacement of a pivoting blade. These figures respectively represent configurations of two opposite blades when the speed of rotation is respectively low, medium and high, the wind speed being constant. In each of these figures, there is shown a pivoting blade 20 exposed to the wind and an opposite pivoting blade 20 ', leeward. The wind-swivel blade 20 and the opposite swivel blade 20 ', downwind, rotate in the direction of rotation Ω. The direction of the wind V is represented by an arrow.

FIG. 2A also shows, in dashed lines, blade positions, called reference positions. Let Δ be an axis, called the blade axis, extending between the leading edge 21 and the trailing edge 22 of a blade. Let A _re f be an axis, referred to as the reference axis, extending between the leading edge 21 and the trailing edge 22 of the blade as it extends in the reference position. Let G be the center of the blade surface. Reference position means a position of a blade according to which the segment, connecting, in a plane XY perpendicular to the central axis of rotation Z, the surface center G of the blade to the central axis of rotation Z , is perpendicular to the reference axis A _re f. When the blades occupy their reference position, the wind turbine is configured like a Darrieus wind turbine. Thus, the reference position of the blade is a position in which at least one section of the blade is oriented parallel to its displacement. The reference axis A _re f of the blade is therefore parallel to the direction of movement of the blade. When the blade is oriented according to the reference position, the trailing edge and the leading edge can in particular be equidistant from the central axis of rotation Z. When the speed of rotation is low, as represented in FIG. 2A, the The blade 20 exposed to the wind tends to incline, so that its trailing edge 22 approaches the central axis of rotation Z. In such a configuration, the trailing edge 22 is closer to the axis of rotation. central point that the firing point 25. The blade axis Δ forms an angle α, said wind angle, relative to the reference axis Δ _Γ βί. The return link 26 tends to limit the angular deflection of the blade 20, and in particular the deflection of the trailing edge 22 with respect to the firing point 25. In other words, the return link 26 tends to limit the approach of the edge of the blade. leakage 22 from the central axis of rotation Z.

When the speed of rotation is low, as shown in Figure 2A, the wind angle is important, for example of the order of 45 °. The wind-exposed blade 20 exerts a driving force, driving the wind turbine in rotation, in a manner analogous to a conventional movable blade panemone. The driving force corresponds to the thrust of the wind on the blade. It is exercised perpendicular to the blade. As the speed of rotation increases, as illustrated in FIGS. 2B and 2C, the return link 26 tends to reduce the wind angle α, thereby reducing the driving contribution of the wind-exposed blade. The blade 20 then tends to approach its reference position. The return link 26 makes it possible to limit the effect of the centrifugal force on the blades, in particular during transient phases occurring when the wind speed fluctuates. The return link 26 also makes it possible to limit the deflection of the point of intersection 27 around the firing point 25.

FIGS. 2A to 2C also show the angular displacement of the opposite blade 20 ', the latter being downwind. If Δ 'and A' _re f respectively represent the axis of the opposite blade 20 ', and the axis of the reference position of the opposite blade, the opposite blade 20' pivots so that the axis of the blade Δ 'forms an angle α', said angle downwind, with respect to the reference axis A ' _re f. The return link 26 'tends to maintain the downwind angle below a low limit value, for example less than 20 ° or 10 °. It tends to limit the spacing of the trailing edge 22 'with respect to the central axis of rotation Z. When the rotational speed is low, the leeward blade 20' has only a marginal drive action relative to With the blade in the wind 20. The higher the speed of rotation, the more the driving contribution of the leeward lee 20 'increases, and becomes predominant beyond a certain speed of rotation. In FIGS. 2A and 2B, the angle a 'is small, typically less than 10 ° or 20 °. In FIG. 2C, the angle a 'decreases further, the opposite blade 20' approaching the reference position. Thus, when the rotational speed is low, the wind turbine rotates in a configuration close to a panemone with moving blades, the driving action being mainly exerted by the blade in the wind 20. When the speed of rotation increases, the wind turbine tends towards a Darrieus type configuration, the blades being oriented according to their respective reference positions. The driving action is then mainly exerted by the leeward lee. In general, the return link 26 makes it possible to limit the angle of inclination α of the blade 20, when it approaches the central axis of rotation, which is less than a first limit angle, the latter being less than or equal to 50 ° or even 45 °. It also makes it possible to limit the angle of inclination a 'of the blade 20, when it moves away from the central axis of rotation, lower than a second limit angle, the latter being less than 10 ° or 20 °. The second limiting angle is smaller than the first limiting angle. The return link 26 thus makes it possible to maintain the trailing edge 22 in a range of predetermined distance with respect to the central axis of rotation Z. The range of distance is reduced as the speed of rotation of the wind turbine increases. Note that unlike the prior art, the second limiting angle, defining the maximum deflection of the blade relative to its reference position, is well below the first limit angle. Thus, the deflection of the blade beyond its reference position is flanged. The deflection of the blade on either side of its reference position is therefore asymmetrical.

FIGS. 3A, 3B, 3C and 3D represent the evolution of a pivoting blade 20 and of an opposite blade 20 'during a half rotation, when the speed of rotation of the wind turbine is low. In these figures, the arm 10 forms an angle with respect to the wind direction V respectively equal to 0 °, 45 °, 90 ° and 135 °. It is observed that the angular clearance of the blades, around their respective pivoting axes, is limited by the return link 26. The wind angle α is large, while the leeward angle α 'is small.

FIGS. 4A, 4B, 4C and 4D show the evolution of a pivoting blade 20 and an opposite blade 20 'during a half rotation, when the speed of rotation of the wind turbine is moderate. In these figures, the arm 10 forms an angle with respect to the wind direction V respectively equal to 0 °, 45 °, 90 ° and 135 °. It is observed that the angular clearance of the blades is limited by the return link 26 and that the angular displacement of the blades, and in particular of the blade in the wind (blade 20 in FIGS 4A and 4B, blade 20 'in FIG. tends to be reduced with respect to the low rotational speed configuration described in connection with FIGS. 3A, 3B, 3C and 3D.

FIGS. 5A, 5B, 5C and 5D show the evolution of a pivoting blade 20 and of an opposite blade 20 'during a half rotation, when the speed of rotation is important. In these figures, the arm 10 forms an angle with respect to the wind direction V respectively equal to 0 °, 45 °, 90 ° and 135 °. According to such a configuration, the angular clearance of the blades is negligible, the blades being oriented according to their reference position. Their pivoting around their respective pivot axes becomes weak. According to this configuration, the blades are arranged in a Darrieus configuration, particularly suitable for exposures to strong winds. The distance between the trailing edge 22 and the central axis of rotation Z is substantially constant during rotation.

Thus, the wind turbine works as well in low wind, because of the angular movement of the blades, as high wind, the wind turbine then presenting a "Darrieus" configuration.

An operating parameter of a wind turbine is the speed parameter λ, also referred to as the specific speed, defined in such a way that:

. u,

At = - or:

v

U designates the peripheral speed of the wind turbine, that is to say the speed of the blade leading edge;

V is the wind speed.

The speed parameter is usually referred to as the "Speed Ratio", meaning speed ratio. Figures 3 to 5 are representative of a start of a wind turbine in moderate or strong wind, the speed parameter λ gradually increasing. FIGS. 3 (3A, 3B, 3C and 3D) show a configuration of the wind turbine at the start-up moment, the speed parameter λ being close to 0. The wind turbine is essentially driven by the wind, similarly to a panemone with movable blades, the angular displacement of the blades being used for the blade to the wind produces a driving force of thrust to increase the rotational speed of the wind turbine. FIGS. 4 (4A, 4B, 4C and 4D) show a configuration of the wind turbine after the acquisition of a certain speed of rotation, the speed parameter λ being close to 1. The contribution to the rotation is balanced between the pale in the wind 20 and the lee in the wind 20 '. The angular displacement of a blade, during a rotation, is reduced. FIGS. 5 (5A, 5B, 5C and 5D) illustrate a configuration of the wind turbine when the rotational speed is higher, the speed parameter λ being 2. The displacement of a blade, during a rotation , is negligible. The wind turbine is then in a Darrieus configuration, the driving force being mainly exerted by the leeward lee.

Thus, at low rotational speed, that is to say at the start of the wind turbine, the angular displacement of each pivoting blade allows the wind turbine to acquire a certain speed of rotation, the driving action being mainly exercised by the blades exposed to the wind, as can be seen in Figures 2A, 3A to 3D. When the rotational speed increases, the angular deflection is reduced little by little (see FIGS. 2B, 4A to 4D), to become negligible, the wind turbine then being in a Darrieus configuration (see FIGS. 2C, 5A to 5D). . The invention thus makes it possible to obtain a Darrieus-type wind turbine, while having a certain efficiency when the wind is weak. This avoids the need for assistance in launching the wind turbine.

FIG. 6 shows a second embodiment, in which the frame 2 of the wind turbine has several arms 10, extending between one end 11 and the central axis of rotation Z. At each end 11 is fixed a pivoting blade 20 Each pivoting blade is associated with an attachment point 15, close to the leading edge 21 and a firing point 25, near the trailing edge 22. Each pivoting blade 20 is rotatable about an axis of pivoting W, parallel to the central axis of rotation Z, and passing through the point of attachment 15. The various blades of the wind turbine are connected to an association link 23, having a star shape, so that that the trailing edge 22 of a pivoting blade 20 is connected to the trailing edge 22 'of several pivoting blades, and in particular of at least one opposite pivoting blade 20', as previously defined. The trailing edge 22 of each pivoting blade is connected to the firing point 25, associated with said blade, by a return link 26, the latter extending between the firing point 25 and the association link 23. intersection of the return link 26 and the association link 23 defines a point of intersection 27. As in the previous embodiment, the association link 23 is articulated according to articulation points, each point of articulation being also a point of intersection. According to this embodiment, the firing point 25 associated with a blade 20 is located near the attachment point 15a of an adjacent pivoting blade 20a. The adjacent pivoting blade is carried by an arm 11a, adjacent to the arm 11 carrying the blade 20. In this figure, the peripheral circle C described by each attachment point 15 is also represented during a complete rotation of the blade. 'wind turbine.

Figure 7 is a photograph of a third embodiment of the wind turbine. According to this embodiment, the wind turbine has four blades. Two blades 20, 20 ', diametrically opposite one another, are pivotable, as previously described. Two other blades 20f, 20f are mounted fixed, in a Darrieus type configuration, that is to say oriented perpendicular to the arm supporting them. The swivel blades are used to start the wind turbine, at low speed. Thus, it is not necessary that all the blades of a wind turbine are pivoting. However, it is preferable that at least two pivoting blades, opposite to each other, are.

Comparative tests were carried out using a wind turbine as represented in FIG. 8A, representative of the invention, and a fixed-blade wind turbine, in a Darrieus configuration, forming a reference wind turbine, the latter being shown in Figure 8B. Each wind turbine has a diameter of 24 cm and has two identical blades, 40 cm high and 6 cm long. The turbines were subjected to a wind whose speed varies between 10 km / h and 65 km / h. It was measured, for different wind speeds, the speed of rotation and the speed parameter λ.

The following table shows the different measured values:

Reference Speed Reference Reference Invention Invention Invention wind

Speed λ Voltage Speed λ Voltage (Km / h) (rev / min) (rev / min) (V)

(V)

10 0 0 0 100 0.44 3

20 80 0.18 2.4 250 0.56 7.5

30 230 0.34 6.9 340 0.52 10.2

40 240 0.26 7.2 373 0.42 11.2

50,260 0.24 7.8 440 0.4 13.2

60,296 0.22 8.9 467 0.352 14

65,307 0.21 9.2 477 0.352 14.3 When the wind speed is low (10 Km / h), the reference wind turbine does not rotate, while the wind turbine according to the invention acquires an already significant rotation speed. In tests involving higher wind speed, the reference wind turbine was launched by hand. At different wind speeds, the speed of rotation of the wind turbine according to the invention is systematically higher than that of the reference wind turbine. FIG. 8C shows the evolution of the rotational speed (ordinate axis) as a function of the wind speed (abscissa axis), respectively for the reference wind turbine (dark bars) and for the wind turbine according to the invention (clear bars).

A converter has been arranged to convert the mechanical energy of each wind turbine into electrical energy, for the power supply of lamps. The circuit diagram of the assembly is shown in FIG. 8D. Three lamps Ll, L2 and L3, of electrical power 1W, were connected between the terminals coming from the wind turbine 1, the terminals being out of phase by 120 ° with respect to each other. The average voltage was measured between two terminals, for example on either side of the lamp L3. The average measured voltage is systematically greater, by at least 50%, by implementing the invention.

Thus, a wind turbine according to the invention makes it possible to obtain, at different wind speeds and with equal blade area, a higher rotational speed than a fixed-blade wind turbine. When the wind speed increases, the speed of rotation of the wind turbine is also higher than the speed of a Darrieus type wind turbine. The wind turbine according to the invention is more adaptable to load fluctuations. Its dynamic behavior allows an optimal adjustment of the orientation of the swivel blades according to the operating conditions, be it a variation of the wind or a fluctuation of the electric charge connected to the wind turbine.

The invention can be implemented for the power supply of habitats, the installation being simple. One can for example consider a coupling of different wind turbines according to the invention. Furthermore, the invention may also be intended for the power supply of isolated dwellings, for example refuges. The dimensions and number of wind turbines will be adjusted to the electrical power to be supplied. Furthermore, the invention can be declined in small wind turbines, the height and / or the diameter is less than 1 m. Such wind turbines are suitable for nomadic uses, for example on recreational vehicles, or even ships.

Claims

1. Wind turbine (1), comprising blades (20, 20 ', 20f, 20f, 20a), configured to rotate about a central axis of rotation (Z) in a direction of rotation (Ω), the axis of central rotation being intended to be oriented vertically, the wind turbine comprising a rigid chassis (2), comprising at least one arm (10) holding the blades, and extending transversely to the central axis of rotation (Z), each blade having a leading edge (21) and a trailing edge (22), so that in the direction of rotation (Ω) the leading edge is disposed in front of the trailing edge, the wind turbine comprising at least two blades (20, 20 '), pivoting blades, each pivoting blade being such that:

the pivoting blade (20) is connected to a point of the arm, said attachment point (15, 15 '), the pivoting blade being rotatable about the point of attachment, along a pivot axis (W, W );

the pivoting blade (20) is connected to another pivoting blade (20 ') by a flexible link (23), said association link;

the wind turbine being characterized in that:

each pivoting blade is associated with a point, called the firing point (25, 25 '), located on the chassis, the firing point being closer to the trailing edge (22) than the leading edge (21), the firing point being closer to the point of attachment than the central axis of rotation (Z);

each pivoting blade is connected to the firing point (25, 25 ') associated with it by a return link (26), fixed at the firing point, extending

between the firing point (25) and a point of intersection (27), located on the association link (23) connected to the blade, the intersection point then corresponding to the intersection between the association link (23) and the return link (26);

Or between the firing point (25) and an intersection point located on the blade, the blade being connected to both the return link (26) and the link (23); so as to limit a movement, relative to the firing point, of said pivoting blade around the pivot axis (W, W).

2. Wind turbine according to claim 1, wherein the firing points (25, 25 '), respectively associated with two different pivoting blades (20, 20'), are different.

Wind turbine according to any one of the preceding claims, wherein the firing point (25) is closer to the central axis of rotation (Z) than the point of attachment (15), or as close to the central axis of rotation (Z) as the point of attachment (15).

Wind turbine according to one of the preceding claims, in which the point of intersection (27) is closer to the trailing edge (22) than to the point of attachment (15).

A wind turbine according to any one of the preceding claims, wherein the association link (23) associated with the pivoting blade (20) extending along a length between said pivoting blade (20) and said other pivoting blade ( 20 '), the firing point (25) is disposed at a distance, less than one-fifth of said length, from the trailing edge (22) of said pivoting blade.

6. Wind turbine according to any one of the preceding claims, wherein the return link (26) is rotatable about the firing point (25).

7. Wind turbine according to claim 6, wherein the return link (26) is fixed to the firing point (25) by a ball joint junction.

8. Wind turbine according to any one of the preceding claims, wherein the firing point (25) is closer to the trailing edge (22) than the attachment point (15).

9. Wind turbine according to any one of the preceding claims, wherein the firing point (25) is fixed on the frame.

10. Wind turbine according to any one of the preceding claims, wherein the firing point (25) associated with a pivoting blade is arranged:

- on the arm (11) maintaining said pivoting blade (20);

or on an arm (11a) adjacent to the arm holding the pivoting blade (20), the adjacent arm holding an adjacent blade (20a) of said pivoting blade.

Wind turbine according to any one of the preceding claims, wherein for each pivoting blade, the return link (26), fixed at the point of fire, extends between the point of fire (25) and a point of intersection. (27), located on the association link (23) connected to the blade, the point of intersection then corresponding to the intersection between the association link (23) and the return link (26), and in which :

the association link (23) extends between two respective association points (28, 28 ') of two pivoting blades (20, 20');

each pivoting blade (20) is connected to the firing point (25):

by a segment (24) of the association link (23), extending between the association point (28) associated with said pivoting blade (20) and the intersection point (27);

And by the return link (26) extending between the point of intersection (27) and the firing point (25).

Wind turbine according to any one of the preceding claims, in which: at least one pivoting blade (20) defines a blade axis (Δ) extending between the trailing edge and the leading edge;

the pivoting blade has a surface center (G);

the pivoting blade corresponds to a position, called the reference, so that when the blade extends in the reference position, the axis of the blade defines a reference axis (A _ref), the reference axis being perpendicular to a straight line, extending perpendicular to the axis of rotation, and connecting the axis of rotation to the surface center of the blade;

the deflection of the trailing edge (22) of the blade being limited so that:

when the blade tilts towards the central axis of rotation (Z), the angle (a) between the blade axis (A) and the reference axis (A _re f) is less than a first angle limit;

when the blade tilts away from the central axis of rotation (Z), the angle (α ') between the blade axis (Δ) and the reference axis (A _re f) is less than at a second limit angle;

the first limiting angle being greater than the second limiting angle.

13. A wind turbine according to claim 12 wherein the first limiting angle is less than or equal to 45 °, and / or the second limiting angle is less than or equal to 20 °.

Wind turbine according to any one of the preceding claims, comprising:

at least two opposite pivoting blades (20, 20 ');

at least two fixed blades (20f, 20f), opposite, connected to an arm, and stationary relative thereto.