Constant-Velocity Drive System for Gimbaled Rotor Hubs

A convertible aircraft comprising at least one tilting rotor movable from a first position in which the or each tilting rotor operates as an airplane propeller to a second position in which the or each tilting rotor operates as a helicopter main lifting rotor, the or each tilting rotor comprising:

• a rotor mast capable of being driven in rotation about its longitudinal axis;
• a hub connected to said mast by a constant velocity drive mechanism and by a tilting arrangement, allowing pivoting of the hub as a whole about any flapping axis converging with the axis of the mast and perpendicular to said axis of the mast, in such a way that said hub is capable of being driven in constant velocity rotation by said mast, about a geometrical axis of rotation of the hub which may be inclined in any direction about the axis of the mast;
• and
• at least two blades, each linked to said hub by a coupling retaining and hinging the blade in pitch;
• wherein said constant velocity drive mechanism comprises a differential mechanism for splitting static torque and allowing relative movement, in a plane perpendicular to said axis of the mast, between at least two devices for driving the hub, said differential mechanism comprising a set of three disks placed substantially one above another and substantially coaxial about said axis of the mast, a first disk of which, arranged between second and third disks of the set along said axis of the mast, is a driving disk, integral in rotation with said mast and connected to each of the second and third disks, which are driven, by at least one connecting pin having a longitudinal geometrical axis substantially parallel to said axis of the mast, and hinged to each of the disks in the set by one respectively of three ball joint connections substantially centered on the longitudinal geometrical axis of said connecting pin, each of the second and third disks being connected to the hub by at least one of said at least two driving devices which are each also hinged to the hub, so as to drive it in rotation about said geometrical axis of rotation of the hub;
• and
• wherein said at least two driving devices are substantially spaced from said differential mechanism along said axis of the mast.

A constant-velocity drive system for a rotary-wing aircraft rotor, the constant-velocity drive system comprising:

• a differential mechanism, the differential mechanism comprising:
• a drive disk adapted to be integral in rotation with a mast;
• an upper member at least partially located above the driven disk;
• a lower member at least partially located below the driven disk;
• at least one link connecting the upper member and the lower member to the drive disk such that the drive disk drives the upper member and the lower member in rotation with the drive disk and that the upper member and the lower member are allowed to rotate differently with respect to the drive disk, the at least one link comprising:
• opposing end joints;
• and
• a central joint;
• wherein the central joint pivotally engages the drive disk;
• and
• wherein each of the end joints pivotally engage one of the upper member and the lower member;
• and
• a gimbal device for driving a rotor hub and for allowing gimbaling of the rotor hub with respect to the mast, the gimbal device being spaced from the differential mechanism along a length of the mast;
• wherein the upper member and the lower member are adapted to drive the gimbal device in rotation;
• and
• wherein each of the opposing end joints and the central joint are ball joints.