Patent attributes
A seat belt retractor has a rotating spool for retraction or pay-out of seat belt webbing. A locking ring is attached to one end of the spool. The locking ring is locked against rotation when a crash is sensed. A force limiting means allows further pay-out of the seat belt webbing after the locking ring has locked. Coupled in the force path between the spool and the locking ring, the force limiting means has a primary force limiting means; and a secondary force limiting means. The force limiting means include an elongate deformable member, arranged such that relative rotation between the spool and the locking ring causes a predetermined length of the deformable member to be deformed during a first stage of load limiting. The cross-sectional area of the deformable member is uniform over a major portion of the predetermined length and is reduced over at least one minor portion located a distance from the end of the member.
