Patent ID: 9181811
Filing Date: 2015-11-10
Classification: B64C,F01D,Y02T

Abstract:
1. A device for varying blade pitch for a rotary wing aircraft including: a main rotor having a plurality of blades; at least one main flap per blade, each main flap being turnable about an axis to modify the pitch of the blade; main actuators controlling the angles of inclination of the main flaps; and a flight control system controlling the main actuators; wherein the device for varying blade pitch comprises at least one secondary flap incorporated in each blade and a swashplate having a non-rotary plate and a rotary plate rotating with the main rotor, the rotary plate acting via a mechanical connection to change the angle of inclination of each main flap and consequently to change the pitch of the corresponding blade, the main actuators being electric actuators for moving and varying the angle of inclination of the non-rotary plate in order to control the main flaps at least cyclically, each secondary flap being subjected to multi-cyclic control by a piezo-ceramic secondary flap electric actuator incorporated in each blade and having a utilization frequency equivalent to at least (b+1)ω, where b corresponds to the number of blades of the main rotor and ω corresponds to the speed of rotation of the main rotor.