Patent ID: 6857978

Claim:
A traction drive for an internal combustion engine, comprising: a belt pulley operatively connected to a crankshaft; a belt pulley operatively connected to a starter-generator; and a tensioning device having two tension pulleys, a traction member for connecting the tension pulleys, two lever arms having different length and constructed for pivoting about a rotation axis, with one tension pulley disposed on one end of one of the lever arms and resiliently bearing against the traction member, and with the other tension pulley disposed on one end of the other one of the lever arms and resiliently bearing against the traction member, wherein the internal combustion engine or the starter-generator selectively introduce a torque into the traction member in dependence on an operating mode of the starter-generator between a starting mode and a normal operating mode, wherein a directional change of the torque is accompanied by a swap between a return strand and a pulling strand of the traction member in the traction drive, wherein the traction member is wrapped about the tension pulleys at different wrap angles, wherein the lever arms extend at an angle of >70° relative to one another, with one lever arm having a length which is at a ratio of 2:1 to a length of the other lever arm, and wherein one tension pulley has a diameter which is greater than a diameter of the other tension pulley.