Safety belt retractor with a belt pretensioner device acting on the belt drum
AssigneeTRW Repa GmbH
InventorBernhard Frei
Life of this patent
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Abstract
A safety belt retractor is provided with a belt pretensioner device acting via a clamping roller coupling mechanism. A torsion rod (30) is arranged in the force flow path between the coupling mechanism and the belt drum (12) of the retractor, so that after tightening of the belt such torsion rod is twisted about its axis under the load transmitted by the belt with the consumption of energy. Owing to the plasitic deformation of the torsion rod (30), it is possible for the load peaks occurring following tightening of the belt in the belt system to be absorbed in order to increase the efficiency of the safety belt system.
Claims8
A safety belt retractor with a frame, a belt drum rotatably mounted in said frame for coiling and uncoiling of belt webbing and a belt pretensioner device comprising a rotary drive with a drive member for rotating, in operation, said belt drum in a coiling direction, said drive member engaging said belt drum through a coupling mechanism and a torsion bar, said torsion bar having a first axial end connected to said belt drum and a second axial end adapted to be engaged by said drive member through said coupling mechanism, said second axial end being free to rotate in said frame with said belt drum in a normal condition where said coupling mechanism is disengaged and coupled with said drive member for joint rotation in an operative condition where said coupling mechanism is engaged, and means for holding said second axial end of said torsion rod fixed against rotation in said frame after operation of said rotary drive while said first axial end of said torsion rod rotates with said belt drum and said torsion rod is twisted under the action of tension occurring in the belt webbing and exceeding a predetermined threshold.
Dependencies are inferred from the claim text.