Patent ID: 7364511

Claim:
A torsional vibration damper, comprising: a primary mass adapted to be coupled to an engine crankshaft for rotation about a rotational axis of the engine crankshaft, the primary mass defining a substantially ring-shaped chamber that is divided into at least two portions; a secondary mass relatively rotatably connected to the primary mass and connectable with a clutch; and a damping unit for coupling the primary and secondary masses to each other in a rotationally elastic manner, wherein the damping unit comprises a plurality of elastic members situated in series and disposed one after the other within the divided portions of the ring-shaped chamber, a pair of end guides slidably disposed within each divided portion of the ring-shaped chamber and supporting outer ends of end ones of the elastic members, and a friction guide disposed between neighboring elastic members and comprising an inner wedge and an outer wedge, each wedge being provided with an outer circumferential surface, the wedges being configured for relative radial movement, during which the outer circumferential surface of the outer wedge is rubbed against an outer wall of the ring-shaped chamber, wherein an oil groove is formed on the outer circumferential surface of at least one of the wedges, and at least a portion of the oil groove is formed to be slanted with respect to a circumferential direction of the ring-shaped chamber.