Energy absorbing torsion bar seat belt retractor with sharp onset property

摘要

An energy absorbing seat belt retractor (20) comprising: a frame (22); a torsion bar (70,70') having a first and a second side, rotationally supported relative to the frame. The torsion bar of the type which is pre-torqued to create a permanent deformation therein or having an annular cross section to reduce a transition zone between the torsion bar's elastic and plastic deformation regions. The retractor also includes a locking device (200) adapted to be activated during a vehicle accident and operative on the first side (76) of the torsion bar to stop the torsion bar from rotating. A spool is operatively connected to the second side of the torsion bar, the spool having a seat belt positioned thereon, wherein with the locking device activated to prevent the first side of the torsion bar from rotating and with a predetermined load communicated to the seat belt, the spool and the torsion bar rotate in a direction of belt protraction opposed by a reaction force generated by the pre-torqued torsion bar as it twists.