Helicopter rotor comprising a vibration damper, and method for updating the same
A rotor for a helicopter, having: a hub rotating about an axis and in turn having a number of blades; and an at least partly hollow drive shaft connectable to a drive of the helicopter and connected functionally to the hub to rotate the hub about the axis; the rotor also having vibration damping means in turn having a mass, and an elastically deformable member connected to the mass and supported by the shaft; the member extending at least partly inside the shaft, and being elongated parallel to the axis; and the mass vibrating, in use, at such a frequency as to oppose transmission to the shaft of the vibration produced by rotation of the hub and blades.
1. A rotor for a helicopter, comprising:
a hub rotating about an axis and in turn comprising a number of blades; and
an at least partly hollow drive shaft connectable to a drive of said helicopter and connected functionally to said hub to rotate the hub about said axis;
and characterized by comprising vibration damping means in turn comprising a mass, and an elastically deformable member connected to said mass and supported by said shaft; said member extending at least partly inside said shaft, and being elongated parallel to said axis; and said mass vibrating, in use, at such a frequency as to oppose transmission to said shaft of the vibration produced by rotation of said hub and said blades and further comprising a supporting body interposed between said shaft and said member, and angularly integral with said shaft and said member.
2. A rotor as claimed in claim 1 , characterized in that said supporting body comprises, at opposite axial ends of the supporting body, a seat engaged by said member, and an end surface fixed to said shaft.
3. A rotor as claimed in claim 1 , characterized in that said member is a rod extending parallel to said axis, and having a first axial end engaged in said seat, and a second axial end opposite said first axial end and fixed to said mass; said rod also comprising an intermediate portion extending between said first and second axial end and through said end surface.
4. A rotor as claimed in claim 1 , characterized in that said mass comprises a main body; and at least one plate connected releasably to said main body to adjust the vibration frequency of said mass.
5. A rotor as claimed in claim 1 , characterized by comprising a flow deflector connected to said hub to direct along a predetermined path the airflow generated in use by rotation of said blades.
6. A rotor as claimed in claim 5 , characterized in that said member and said mass are housed in a cavity defined by said flow deflector and said shaft; said cavity isolating said vibration damping means from said hub.
7. A rotor as claimed in claim 5 , characterized in that said mass is housed in said flow deflector.
8. A rotor as claimed in claim 1 , characterized in that said member, said supporting body, and said mass extend symmetrically about the axis.
9. A helicopter, characterized by comprising a rotor as claimed in claim 1 .
10. A method for updating a rotor of a helicopter;
said rotor comprising:
a hub rotating about an axis and in turn comprising a number of blades; and
an at least partly hollow drive shaft connectable to a drive of said helicopter and connected functionally to said hub to rotate the hub about said axis;
said method being characterized by comprising the steps of:
inserting a resilient deformable member at least partly inside said shaft, and securing it to said shaft;
interposing said member between said shaft and a mass; and
interposing a supporting body between said shaft and said member, and angularly integral with said shaft and said member;
said member and said mass defining vibration damping means for damping vibration produced by rotation of said hub and said blades; and said mass vibrating, in use, at such a frequency as to oppose transmission to said shaft of the vibration produced by rotation of said hub and said blades.