WINDSCREEN

Abstract

The present invention relates to a wind turbine (1) comprising at least one base (2), a shaft (3) extending along an axis of rotation (A) and capable of rotating about said axis of rotation (A) relative to the base (2), a rotor (4) fixed to the shaft (3) comprising at least two arms (5, 6, 7, 8) each extending along a respective arm axis (B1, B2, C1, C2), and a disc-shaped blade (9, 10, 11, 12) fixed to one end of each arm (5, 6, 7, 8), which disc-shaped blade (9, 10, 11, 12) is fixed perpendicularly to the axis of the arm (B1, B2, C1, C2). Abbreviated figure: Figure 1

Description

Title of the invention: WIND TURBINE FIELD OF THE INVENTION

[0001] The present invention relates to a wind turbine. PREVIOUS ART

[0002] It is known to produce electricity from the force of the wind by means of a wind turbine. Said wind turbine can rotate relative to a fixed base, containing a generator.

[0003] Most wind turbines developed in recent decades are horizontal axis wind turbines (HAWTs) with a growing trend towards gigantism. This trend leads to a centralized energy production model with very high operating costs, visual and noise pollution, bird casualties and inefficient land use due to strict safety regulations. For all these reasons, HAWTs are not very popular and will never find their place in urban areas.

[0004] Vertical axis wind turbines (VAWTs) are an attractive alternative because they can produce more power with less space, are safe for birds, much quieter, and have lower operating costs because critical components are located at ground level, making them easier to maintain. The compactness of VAWTs makes them better suited to urban environments and local energy production and management—i.e., microgrids or local power grids.

[0005] VAWTs also have very interesting characteristics for floating offshore wind farms. This rapidly expanding market makes it possible to exploit previously inaccessible offshore wind resources, with much higher wind quality offering very high energy production potential. Here, VAWTs make it possible to significantly reduce operating costs compared to HAWTs, on the one hand for the installation and maintenance of the stability of the wind turbines, and on the other hand for the accessibility of critical components on the surface and not at the top of a 200 to 300 m high tower.

[0006] However, the vertical axis wind turbine industry has been hampered to date by historical malfunctions of high-power Darrieus turbines, which have proven difficult to implement on a large scale. As a result, improvements to the design of the most popular VAWTs, namely the H-type Darrieus models, are welcome in order to increase their cost-effectiveness and power density for a given footprint. Summary of the invention

[0007] The invention relates to a wind turbine comprising at least one base, a shaft extending along an axis of rotation and rotatable about said axis of rotation relative to the at least one base, a rotor fixed to the shaft comprising at least two arms, each arm extending along a respective arm axis, and a disc-shaped blade fixed to one end of each arm, wherein said disc-shaped blade is fixed perpendicular to the arm axis, preferably the disc-shaped blades have an aerodynamic profile of an aircraft wing.

[0008] Compared to conventional wind turbine blades with the same vertical and horizontal footprint, circular blades offer a much larger wind-catching surface, thus providing more energy than the former.

[0009] Typically, a conventional blade 5 meters high with a width of 50 centimeters will have a wind catch surface of 2.5 m2 compared to a circular blade 5 meters in diameter with a wind catch surface of 19.6 m2.

[0010] Furthermore, it appears that circular blades fixed in this way are very quiet and less subject to mechanical vibrations.

[0011] Finally, these circular blades fixed in this way seem safer than traditional blades, because they are less sensitive to breakage.

[0012] In conclusion, the circular blades fixed in this way make it possible to obtain a more efficient, safer, quieter and less expensive wind turbine.

[0013] Specific features or embodiments, usable alone or in combination, are:

[0014] - the axis of rotation is vertical for a vertical axis wind turbine or horizontal for a horizontal axis wind turbine,

[0015] - the rotation axis is arranged vertically for a vertical axis wind turbine (VAWT),

[0016] - the axis of rotation can also be arranged horizontally, the wind turbine comprising preferably two bases, one base being arranged at each end of the shaft.

[0017] - an arm axis belongs to a plane perpendicular to the axis of rotation,

[0018] - the attachment of the blade to the arm is centered,

[0019] - the rotor is axisymmetric: each of the at least two arms has the same length, is arranged equiangularly around said axis of rotation and all the blades are identical,

[0020] - at least one of the at least two arms has a greater length and its blade is reduced size, so as to restore the balance of the rotor,

[0021] - the blades have an aerodynamic profile of an aircraft wing, preferably a profile NACA (National Advisory Committee for Aeronautics), and preferably one more NACA 0012 profile,

[0022] - the number of arms is between 2 and 8. DESCRIPTION OF FIGURES

[0023] The invention will be better understood on reading the following description, which is purely illustrative and with reference to the appended figures in which:

[0024] [Fig.l] shows, in perspective view, a symmetrical embodiment of a wind turbine according to the invention.

[0025] [Fig.2] shows the same embodiment of wind turbine in side view.

[0026] [Fig.3] shows the blade used in this embodiment of wind turbine in side view compared to a conventional blade.

[0027] [Fig.4] shows the same embodiment of wind turbine in top view.

[0028] [Fig.5] shows in side view the detail of the aerodynamic profile of the blade used in this embodiment of wind turbine,

[0029] [Fig.6] shows in top view the aerodynamic profile of the blade used in this wind turbine construction method.

[0030] [Fig.7] shows, in front view, the aerodynamic profile of the blade still used in this embodiment of wind turbine.

[0031] [Fig.8] shows a perspective view of another symmetrical embodiment of a wind turbine according to the invention, said wind turbine comprising four branches.

[0032] [Fig.9] shows a perspective view of the blade used in this embodiment wind turbine.

[0033] [Fig. 10] shows a top view of the wind turbine embodiment of [Fig.8].

[0034] [Fig. 11] shows a top view of an asymmetrical embodiment of a wind turbine according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] With reference to [Fig.l], the invention relates to a wind turbine 1. Said wind turbine 1 comprises a base 2 which is generally fixed and fixed to the ground. The wind turbine 1 further comprises a shaft 3. Said shaft 3 extends along an axis of rotation A. Said shaft 3 is rotatable about said axis of rotation A relative to the base 2.

[0036] The wind turbine 1 further comprises a rotor 4. This rotor 4 is preferably axisymmetric. In the present case, the axisymmetry is with respect to the axis of rotation A. The rotor 4 is fixed to the shaft 3. The rotor 4 comprises at least two arms 5, 6, 7, 8. An example with four arms 5, 6, 7 and 8 is illustrated in figures 8 and 10. Said arms 5, 6, 7, 8 are preferably arranged axisymmetrically, i.e. 2 arms at 180°, 3 arms at 120°, 4 arms at 90°, 5 arms at 72°, and so on. Each of said arms 5, 6, 7, 8 extends along its respective arm axis, axis B1, B2 in the embodiment of figures 1 and 2. Each arm 5, 6, 7, 8 is preferably arranged in the same plane per- pendulum to the axis of rotation A.

[0037] The number of arms 5, 6, 7, 8 can be any. The figures represent a rotor 4 with two or four arms.

[0038] According to one feature, the number of arms 5, 6 is at least 2 and can be extended to any number. The limitation comes only from the size. A reasonable maximum number is 8. Preferably, the number of arms is between 2 and 6, preferably between 3 and 5.

[0039] Each arm connected to the rotor is fixed to a blade. Now, the arm can be made up of several elements. As illustrated in Figures 8, 9 and 10, the wind turbine comprises four arms 5, 6, 7, 8, each arm being made up of two straight spars 5', 5" (for example, steel spars) and each arm being fixed by its two straight spars to a blade 9, 10, 11, 12 in the shape of a disc having an aerodynamic profile of an aircraft wing.

[0040] Thus, according to yet another characteristic, each arm 5, 6, 7, 8 comprises one or more side members, preferably between 1 and 3 side members. Alternatively, the arm may also have a lattice structure.

[0041] The wind turbine 1 further comprises a blade 9, 10, 11, 12 per arm 5, 6, 7, 8. Said blade 9, 10, 11, 12 is fixed to one end of the arm 5, 6, 7, 8.

[0042] According to a main characteristic of the invention, said blade 9, 10, 11, 12 is disc-shaped and is fixed to the end of an arm 5, 6, 7, 8, perpendicular to the axis of the arm B1, B2, C1, C2. [Fig. 3] shows comparatively the wind-catching surface for a conventional blade C and the wind-catching surface for a blade according to the invention I, showing the advantage of the disc-shaped blade 9, 10.

[0043] According to another characteristic, an arm axis B1, B2, Cl, C2 belongs to a plane perpendicular to the axis of rotation A.

[0044] According to yet another characteristic, the fixing of the disc-shaped blade 9, 10, 11, 12 is preferably centered in the sense that the center of the end of the arm 5, 6, 7, 8 comes into abutment at the center of the disc of the blade 9, 10, 11, 12.

[0045] According to a preferred characteristic, for rotational balance, the rotor 4 is axisymmetric: the at least two arms 5, 6, 7, 8 are of the same length, are arranged equiangularly around said axis of rotation A and the blades 9, 10, 11, 12 are identical and oriented in an identical manner.

[0046] As illustrated in [Fig.4], a blade 9, 10 has, in a plane perpendicular to the axis of rotation A and passing through the arm axis B1, B2, an aircraft wing aerodynamic profile, while retaining a circular shape. In this case, the corresponding aircraft wing aerodynamic profile is a NACA 0012 profile.

[0047] Thus, the blades have an aerodynamic profile of an aircraft wing, preferably a NACA profile, and particularly preferably a NACA 0012 profile.

[0048] An illustrative embodiment of said aerodynamic profile is shown in Figures 5 to 7 showing a particular blade 7, 8 from three different viewpoints. The values ​​indicated in Figures 5 to 7 are only indicative and are provided only to give an indication of the proportions. The exact size of the blade 7, 8 can be any.

[0049] The wind turbine 1 of the invention is primarily intended to be mounted with a vertical axis of rotation A. However, this does not preclude use with a horizontal axis of rotation A, for example between two buildings. In this configuration, the shaft 3 may be held by two bases, one base in each of the two buildings.

[0050] A problem may arise with such a type of wind turbine, particularly when the rotation axis A is arranged vertically. This problem is that the rotor 4 may remain stationary when it is positioned in a particular orientation relative to the wind. This is called the self-start problem.

[0051] The problem of automatic start-up is well known. When starting from a static position, a rotor 4 with a vertical axis of rotation A may encounter, at a given angle relative to the direction of the wind, a position where the force applied by the wind to the first blade 7 creates a momentum around the axis A which corresponds exactly to the momentum created by this same wind on the second blade 8. In this case, the two momentums oppose and cancel each other out. The rotor 4 then remains static and does not start its rotation.

[0052] One way to correct this problem is to shift the axis of the shaft 3, in order to slightly unbalance the rotor 4, thus breaking the axisymmetry.

[0053] According to [Fig.l 1], the axis of the shaft 3 is offset from the center 13 of the rotor 4. This leads to at least one of the at least two arms 5, 6 (i.e. arm 6 in [Fig.l 1]) having a greater length. This offset prevents the automatic start problem from occurring.

[0054] To compensate for said imbalance, and restore the balance of the rotor 4 at least in terms of momentum, the blade 7, 8 attached to the at least one longer arm 5, 6 is reduced in size accordingly. This reduction concerns the thickness of the profile and the height / diameter. This reduction is preferably homothetic. The rule for determining the decrease of the blade is to conserve the kinetic moment, that is to say that the mass of each wing 7, 8 times the length of its arm 5, 6 must be equal.

[0055] The invention has been illustrated and described in detail in the drawings and the foregoing description. Said description should be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Several alternative embodiments are possible. List of reference signs

[0056] 1: wind turbine,

[0057]

[0058]

[0059]

[0060]

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[0063]

[0064] 2: base, 3: shaft, 4: rotor, 5, 6, 7, 8: branch, 9, 10, 11, 12: blade, 13: center A: axis of rotation, Bl, B2,C1,C2: axis of the arm.

Claims

Claims

1. A wind turbine (1) comprising at least one base (2), a shaft (3) extending along an axis of rotation (A) and rotatable about said axis of rotation (A) relative to the at least one base (2), a rotor (4) fixed to the shaft (3) comprising at least two arms (5, 6, 7, 8) each extending along a respective arm axis (B1, B2, C1, C2) and a disc-shaped blade (9, 10, 11, 12) fixed to one end of each arm (5, 6, 7, 8), characterized in that said disc-shaped blade (9, 10, 11, 12) is fixed perpendicularly relative to the arm axis (B1, B2, C1, C2), preferably said disc-shaped blade (9, 10, 11, 12) has an aerodynamic profile of airplane wing.

2. The wind turbine (1) according to claim 1, wherein said attachment is centered in that the center of the end of the arm (5, 6, 7, 8) abuts the center of the blade disc (9, 10, 11, 12).

3. The wind turbine (1) according to any one of claims 1 or 2, wherein the axis of rotation (A) is arranged vertically.

4. The wind turbine (1) according to any one of claims 1 to 3, wherein the arm axis (Bl, B2, Cl, C2) belongs to a plane perpendicular to the axis of rotation (A).

5. The wind turbine (1) according to any one of claims 1 to 4, wherein the blades (9, 10, 11, 12) have a NACA (National Advisory Committee for Aeronautics) profile, preferably a NACA 0012 profile.

6. The wind turbine (1) according to any one of claims 1 to 5, wherein the number of arms (5, 6, 7, 8) is between 2 and 8, preferably between 2 and 6 and, most preferably, between 3 and 5.

7. The wind turbine (1) according to any one of claims 1 to 6, wherein each arm (5, 6, 7, 8) comprises one or more spars, preferably between 1 and 3 spars.

8. The wind turbine (1) according to any one of claims 1 to 6, wherein each arm (5, 6, 7, 8) has a lattice structure.

9. The wind turbine (1) according to any one of claims 1 to 8, wherein the rotor (4) is axisymmetric: each of the at least two arms (5, 6, 7, 8) has the same length, is arranged equiangularly around said axis of rotation (A) and each blade (9, 10, 11, 12) is identical.

10. The wind turbine (1) according to any one of claims 1 to 8, wherein at least one of the at least two arms (5,6,7,8) is of a greater length and its blade (9,10,11,12) is smaller in size so as to restore the balance of the rotor (4).

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