Device for producing electric current from wind energy

1. A system for producing electricity from wind energy, the system comprising a vertical mast having a bottom end portion fixed to a support surface, a nacelle mounted to turn about a vertical axis on atop end portion of the mast, a rotary portion comprising a hub and two or more substantially radial blades fixed to the hub, a bearing in which the rotary portion rotates and which has a substantially horizontal axis, and an electricity generator comprising a stator secured to the nacelle and a rotor secured to the hub of the rotary portion by a fixing member substantially perpendicular to the rotation axis of the rotary portion, wherein:

both the rotor and the stator have respective active portions each in the form of a disk carrying facing electromagnetic members,

the rotary portion rotates on the nacelle in a single bearing whose diameter is 80%-100% the diameter of a circle inscribed in the cross section perpendicular to the axis of the rotary portion of a surface formed by areas in which the blades are connected to the hub, and

the fixing member fixing the rotor to the hub is adjacent the bearing along the axial direction of the bearing.

2. A system according to claim 1 , wherein the fixing member connecting the rotor to the hub is annular and has an inner portion connecting it to the hub and to a rotary inner race of the rolling bearing between the hub and the bearing in the axial direction of the hub and the bearing, to both of which the fixing member is rigidly fixed.

3. A system according to claim 1 , comprising a first subassembly comprising a main frame rotatably mounted on the top portion of the mast, a second subassembly fixed to the first subassembly at a junction plane and comprising, on a support frame, the electricity generator including the stator, the rotor, and the bearing, and a third subassembly connected to the second subassembly at the location of the bearing and comprising the hub and the blades of the rotary portion, the three subassemblies being interconnected by flanges to absorb forces exerted by the wind on the rotary portion on the first subassembly via the second subassembly, the first subassembly enclosing a plurality of preselected system components.

4. A system according to claim 1 , wherein the active portions in the form of disks of the rotor and the stator are separated by an airgap whose width is adjusted so that the stator exerts on the rotor and on the rotary portion an axial force in the opposite direction to the axial force exerted by the wind on the rotary portion.

5. A system according to claim 1 , further comprising a mechanical brake for the rotary portion including a disk brake whose disk is secured to the rotor of the electricity generator and which includes a plurality of calipers for braking the disk distributed around the outside periphery of a portion of a frame of the nacelle.

6. A system according to claim 5 , further comprising an aerodynamic braking system including radial end portions of the blades opposite the ends of the blades connected to the hub, adapted to rotate about a longitudinal axis of the corresponding radial blade and connected to a system for pivoting the end portion of the blade as a function of the wind speed or the speed of rotation of the rotary portion.

7. A system according to claim 1 , wherein the bearing is a rolling bearing and the nacelle includes a system for lubricating the rolling bearing.

8. A system according to claim 1 , wherein the bearing is adjacent the hub in the axial direction so that the rotary portion of the system is fixed to the frame of the nacelle with a cantilever that is small.

9. A system according to claim 1 , wherein an active portion of the rotor in the form of a disk carries permanent magnets distributed in the circumferential direction of the active portion of the rotor.