Mechanism for eliminating limit cycle oscillations on servocontrolled aerodynamic control surfaces
Servocontrolled aerodynamic control surfaces, such as the direction rudder ( 1 ) of an airplane, are equipped with servoactuators ( 5 ). The bearing supports ( 3 ) of the rotation axis ( 2 ) or hinged axis give rise to the formation of free play for the manufacturing tolerances, that will be more pronounced with the wear of the bearings or joint elements. The mechanism ( 8 ) in question includes an elastic element ( 10 ) fixed to the structure ( 4 ) wherein the control surface ( 1 ) is jointed, connected rigidly to an articulated connecting rod ( 12 ) having a following roller ( 13 ) of a cam ( 9 ) integral to the control surface ( 1 ). The cam ( 9 ) profile produces a continuous nonlinear, angular deformation, of the elastic element in order to determine a force torque on the control surface ( 1 ) that is maximum in the neutral position of the control surface and manages to be eliminated in the extreme side deviations.
1. Mechanism for eliminating limit cycle oscillations for servocontrolled aerodynamic control surfaces fixed to a structure, equipped with servoactuators and whose supports of the rotation axis or the hinged axis, determine free play due to the manufacturing tolerances and the wear of the bearings or joint elements, wherein said mechanism for eliminating limit cycle oscillations comprises
an elastic element, spring or torsion bar, fixed to the structure wherein the control surface is jointed,
an articulated rod rigidly connected to a free end of the elastic element, said articulated rod comprising a roller at a free end thereof
a cam integral to the control surface,
being the roller of the rod a following roller of the cam, in such a way that the following roller permanently contacts the cam, and deviations of the control surface together with the profile of the cam produce continuous nonlinear angular deformation of the elastic element, defining said angular deformation a force torque on the control surface, that reduces when the deviations of the control surface increase, being “0” for positive and negative deviations of the control surface that exceed a pre-established angular value.
2. Mechanism for eliminating limit cycle oscillations according to claim 1 wherein the elastic element is fixed to the structure by means of a disk, being the joining of the elastic element to the disk accomplished by means of an anchoring point having a square section.
3. Mechanism for eliminating limit cycle oscillations according to claim 1 , wherein the elastic element is connected to the articulated rod by means of a support bearing and the angular deformation of the elastic element is controlled by said support bearing.
4. Mechanism for eliminating limit cycle oscillations according to claim 2 , wherein the elastic element is connected to the articulated rod by means of a support bearing and the angular deformation of the elastic element is controlled by said support bearing.
5. Arrangement of a servocontrolled aerodynamic control surface fixed to a structure, equipped with servoactuators and whose supports of the rotation axis or the hinged axis, determine free play due to the manufacturing tolerances and the wear of the bearings or joint elements, wherein said arrangement of a control surface comprises a mechanism for eliminating limit cycle oscillations, said mechanism for eliminating limit cycle oscillations comprising:
an elastic element, spring or torsion bar, fixed to the structure wherein the control surface is jointed,
an articulated rod rigidly connected to a free end of the elastic element, said articulated rod comprising a roller at a free end thereof, and
a cam integral to the control surface,
being the roller of the rod a following roller of the cam, in such a way that the following roller permanently contacts the cam, and deviations of the control surface together with the profile of the cam produce continuous nonlinear angular deformation of the elastic element, defining said angular deformation a force torque on the control surface, that reduces when the deviations of the control surface increase, being “0” for positive and negative deviations of the control surface that exceed a pre-established angular value.