Patent ID: 8430350

Claim:
A seat belt retractor comprising: a spool for retracting a seat belt, wherein the spool has one side in an axial direction of the spool and another side in the axial direction of the spool; a torsion bar disposed inside the spool, wherein the torsion bar has one side in an axial direction of the torsion bar and another side in the axial direction of the torsion bar, wherein the one side of the torsion bar is connected to the one side of the spool, and wherein the torsion bar is configured to be capable of absorbing energy of movement of an occupant while being deformed under torsion by a relative displacement of the one side of the torsion bar and the another side of the torsion bar; a pre-tensioner positioned at the another side of the spool and configured to generate a rotating drive force for rotating the spool in a retracting direction of the seat belt in a condition of rapid deceleration of a motor vehicle; and a first locking device positioned at the another side of the spool and capable of locking the another side of the torsion bar such that a rotation of the spool in a withdrawal direction of the seat belt is suppressed when the pre-tensioner is not activated; and wherein, in an operating time of the pre-tensioner, the pre-tensioner is configured to be a second locking device to lock the another side of the torsion bar by retaining pressure generated by the pre-tensioner to suppress a rotation of the another side of the torsion bar in the withdrawal direction of the seat belt for a predetermined period.