Vibration damping device for motor vehicle transmission drivetrain

A damping device for damping torsional vibrations of a motor vehicle transmission drivetrain, the damping device comprising:

• a first element (3) and a second element (2, 102) rotationally movable around a rotation axis X;
• an elastic damping member coupling the first element (3) and the second element (2, 102) to allow torque transmission with vibration damping between the first element (3) and the second element (2, 102), the torque transmission with damping being accompanied by relative rotation between the first element (3) and the second element (2, 102);
• and
• a rolling body moveable with respect to the second element along a curvilinear trajectory over at least a predetermined angular sector (A);
• the elastic damping member including at least one elastic blade (13, 14, 113, 114) mounted rotationally integrally with the first element (3);
• movement of the rolling body along the curvilinear trajectory with respect to the second element being accompanied by a movement of the rolling body on the at least one elastic blade, causing the at least one elastic blade to flex;
• a first raceway (17, 117) and a second raceway (18, 118) carried respectively by the at least one elastic blade (13, 14, 113, 114) and by the second element (2);
• the rolling body (15, 16, 115, 116) configured to move on the first raceway (17, 117) and the second raceway (18, 118) in order to allow angular deflection between the first element (3) and the second element (2, 102);
• the first raceway (17, 117) and the second raceway (18, 118) configured so that in a relative angular position between the first element (3) and the second element (2, 102) which differs from an inactive relative position, the rolling body (15, 16, 115, 116) exerts a flexural load on the at least one elastic blade (13, 14, 113, 114), producing an opposite reaction force of the at least one elastic blade (13, 14, 113, 114) on the rolling body (15, 16, 115, 116);
• the opposite reaction force having a circumferential component capable of returning the first and second elements (2, 102, 3) to the inactive relative position;
• each of the first and second raceways (117, 118) having a tooth set, and the rolling body (115, 116) being a sprocket having a tooth set meshing with the tooth sets of the first and second raceways (117, 118).