US Patent 7140966 Torsional vibration damper

A torsional vibration damper is provided which comprises a primary mass, a secondary mass, and a damping unit. The primary mass defines a ring-shaped chamber, and the ring-shaped chamber is divided into at least two portions. The secondary mass is rotatably connected to the primary mass. The damping unit couples the primary and secondary masses to each other in a rotationally elastic manner. The damping unit comprises a plurality of elastic members, a pair of end guide, and a friction member disposed between the elastic members.