Patent ID: 7004866
Filing Date: 2006-02-28
Classification: F16H

Abstract:
1. A shiftable toothed-belt drive comprising: a drive set comprising at least two toothed gearwheels rotatable on axially parallel radially offset axes, the gearwheels being radially spaced at a distance from each other, each of the gearwheels having respective similarly shaped toothing, a first one of the gearwheels has axially opposite sides; a belt which extends around the gearwheels and the belt having an inside with internal toothing shaped for meshing with the toothing of the gearwheels, the belt having an outside; an engagement and disengagement device positioned to act on the belt for selectively causing meshing of the toothing of the belt with the toothing on a first one of the gearwheels and for demeshing the belt from the toothing on the first gearwheel, the engagement and disengagement device being connected with the belt for lifting the belt radially from the first gearwheel from a meshed position into a demeshed position or for moving the toothed-belt radially so that the toothing thereon meshes with the toothing of the first gearwheel with the belt moving from the demeshed position into the meshed position; the engagement and disengagement device further comprises: a split belt pulley comprised of two pulleys, each pulley being respectively arranged at a respective axially opposite side of the first gearwheel and each pulley being respectively freely rotatable in relation to the first gearwheel, wherein the pulleys have axes of rotation which are in alignment with the axis of rotation of the first gearwheel; each of the pulleys has an annular, radially outwardly facing, belt running surface which is oriented to descend radially in the direction toward the first gearwheel and toward the other one of the pulleys and the running surfaces being oriented obliquely to the axis of rotation of the pulleys, wherein the belt running surfaces of the two pulleys define between them a generally V-shaped groove on which the toothed belt is received; at least one of the two pulleys being arranged to be axially movable in relationship to each other and in relationship to the first gearwheel; the engagement and disengagement device further comprises a disengager positioned and connected for acting on the pulleys and for applying a disengagement force which urges the pulleys axially in the direction toward the belt and for pushing the pulleys axially toward one another to an extent such that when the toothed belt is running on the belt running surfaces of the pulleys, the belt running surfaces of the pulleys raise the toothed belt radially from the first gearwheel for moving the belt at the first gearwheel from the meshed position to the demeshed position; the engagement and disengagement device further comprises an engager selectively movable into contact with the outside of the toothed belt, the engager being moveable transversely to the rotation axis of the first gearwheel and being moveable for applying an engagement force to the outside of the toothed belt for tensioning the toothed belt to a sufficient extent that the belt pressure on the running surfaces presses the two pulleys axially away from one another to an extent that when the toothed belt runs on the belt running surfaces of the pulleys, the toothed belt becomes seated radially onto the gearwheel such that the toothed belt is moved from the demeshed position to the meshed position with the gearwheel.