Sensor device for measuring aerodynamic loads of a rotor blade of a wind turbine

1. A sensor device for measuring aerodynamic loads of a wind turbine rotor blade comprising:

a reflector arranged in a cavity of a rotor blade extending from a rotor hub;

a signal evaluation device arranged at a distance from the reflector and operable to receive a signal from the reflector, the signal evaluation device detecting and quantifying a physical change of the rotor blade from the reflector signal; and

a cleaning device associated with the reflector for cleaning the reflector, the cleaning device activated by a centrifugal force during rotation of the rotor hub; and

wherein the cleaning device is operable for activation when the rotor hub is rotating slowly and deactivation when the rotor hub is rotating quickly.

2. The sensor device of claim 1 wherein the reflector has a reflector surface arranged substantially transverse to a path of the signal and which is cleaned by the cleaning device.

3. The sensor device of claim 2 wherein the reflector in a direction of the signal evaluation device comprises a protective shield arranged in front of the reflector surface and which does not interfere with the signal, a surface of the protective shield points in the direction of the signal evaluation device and is cleaned by the cleaning device.

4. The sensor device of claim 3 wherein the protective shield, together with the reflector surface, forms a solid bond that is impenetrable to air.

5. The sensor device of claim 3 wherein the reflector and the protective shield are arranged in a housing.

6. The sensor device of claim 5 wherein the protective shield forms a cover for the housing arranged in the direction of the signal evaluation device and the cleaning device is arranged on the surface of the protective shield pointing in the direction of the signal evaluation device.

7. The device of claim 3 wherein the protective shield is arranged in relation to the reflector surface in a plane that is angled and opens out in the direction of a signal path.

8. The sensor device of claim 3 , wherein the cleaning device comprises a wiper device with a wiper arm operable to swivel back and forth across a reflector surface, and wherein the wiper arm in its starting position is supported adjacent a side edge of the protective shield surface and in a wiping position rotates over the protective shield surface.

9. The sensor device of claim 1 , wherein the cleaning device comprises a wiper device with a wiper arm operable to swivel back and forth across a reflector surface.

10. The sensor device of claim 9 , wherein the wiper arm further comprises a sealing lip pointing in the direction of the reflector surface, wherein the wiper arm is rotatable from a starting position into a wiping position over the reflector surface, and in the starting position is arranged at a side edge of the reflector surface.

11. The sensor device of claim 9 , wherein the wiper arm is activated as a function of rotor hub rotation.

12. The sensor device of claim 11 , wherein the wiper arm only wipes across the reflector surface when the rotor hub is rotating at low speeds and remains in the starting position when the rotor hub is rotating at high speeds.

13. The sensor device of claim 12 , wherein at low rotor speed the wiping across the reflector surface takes place by means of the force of gravity (g) acting on the reflector as a result of rotation of the rotor blade.

14. The sensor device of claim 11 , wherein the wiper arm remains in the starting position when the centrifugal force acting on the reflector is high.

15. The sensor device of claim 1 in combination with wind turbine comprising:

a rotor that can rotate about a rotor axis by wind power, the rotor having a rotor hub and at least one rotor blade secured to the rotor hub and extending therefrom in a direction substantially transversal to the rotor axis;

at least one electrical generator, which is mechanically coupled to the rotor and driven thereby.

16. A sensor device for measuring aerodynamic loads of a wind turbine rotor blade comprising:

a reflector arranged in a cavity of a rotor blade extending from a rotor hub;

a signal evaluation device arranged at a distance from the reflector and operable to receive a reflector signal from the reflector, the signal evaluation device detecting and quantifying a physical change of the rotor blade from the reflector signal;

a cleaning device associated with the reflector for cleaning the reflector, the cleaning device being activated by a centrifugal force generated during rotation of the rotor hub, the cleaning device being activated in response to an increase in hydraulic or pneumatic pressure with increasing centrifugal force.

17. The sensor device of claim 16 , wherein the cleaning device comprises a sprayer having a storage tank adapted to be filled with a cleaning agent, an activation unit that responds to the centrifugal force, and a line in fluid communication between the storage tank and a discharge nozzle arranged on the sensor device.