Vehicle belt drive torsion bar tensioner with an improved damping device

A tensioner for a vehicle belt drive, having a housing defining a cavity having an axis (A); at least one arm fitted to the housing to rotate about the axis (A); an idle pulley fitted to the arm; a torsion bar elastic member housed at least partly in the cavity and having a first end portion integral with the arm, and a second hand portion connected rigidly to a retaining portion to permit tensioning of the elastic member; and a damping device for damping oscillation of the arm, and having a conical friction member cooperating axially with a mating surface and loaded by axial elastic means. The friction member is interposed between the arm and the housing; and the elastic member produces an axial thrust component depending on torsion of the elastic member and for pressing the friction member and the mating surface.