Patent ID: 7985151
Filing Date: 2011-07-26
Classification: F16H

Abstract:
1. A tensioning device of a traction mechanism drive, comprising: a tensioning lever which is mounted on a base housing so as to be able to rotate via a pivot bearing and, radially spaced apart from the axis of rotation of the pivot bearing, is provided with a rotatable tensioning roller, which tensioning lever can, by means of a torsional spring which is configured as a helical spring, is arranged coaxially with the pivot bearing and is connected at both spring ends at the housing side to the base housing and at the lever side to the tensioning lever, be acted on with a torsional moment about the axis of rotation of the pivot bearing, the pivot bearing comprising a bearing journal, a bearing hub and at least one plain bearing sleeve arranged between the bearing journal and the bearing hub, and a central radial force application plane of the tensioning roller being axially spaced apart from a central radial bearing plane of the pivot bearing, characterized in that the torsional spring is configured as a legless helical spring which can be loaded in the opening direction and has blunt spring ends, the lever-side spring end of said helical spring resting against an axially/radially oriented stop surface of an entrainment member connected to the tensioning lever, the entrainment member being arranged at the circumferential side with respect to the axis of rotation of the pivot bearing in such a way that the stop surface is oriented normally to a resulting reaction force of a traction mechanism onto the tensioning roller, a reaction force of the tensioning lever onto the helical spring being supported relative to the base housing, and the center of the lever-side spring end being axially spaced apart from the central bearing plane of the pivot bearing in such a way that the tilting moments of a tangential spring force, which acts on the tensioning lever via the stop surface, of the helical spring and of the resulting reaction force, which acts on the tensioning lever via the tensioning roller, of the traction mechanism cancel one another out about a notional tilt axis which perpendicularly intersects the axis of rotation of the pivot bearing in the central bearing plane perpendicularly to the spring force and the reaction force.