| 摘要 |
A seat belt retractor (10) comprises a rotatable spool (16) with seat belt webbing (18) wound around the spool. The spool (16) has a longitudinal central axis and is rotatable in a belt unwinding direction (20) about its longitudinal central axis to enable the seat belt webbing (18) to be extended about a vehicle occupant. An actuatable locking mechanism (60), when actuated, prevents the spool (16) from rotating in the belt unwinding direction (20). A toothed wheel (24) is rotatable with the spool (16) about the longitudinal central axis of the spool. The toothed wheel (24) includes at least one coded tooth (26') comprising magnetic material. A pair of magnetic sensors (30, 35) cooperates to sense rotation of the coded tooth (26') about the longitudinal central axis of the spool (16). The locking mechanism (60) actuates to prevent the spool (16) from rotating in the belt unwinding direction (20) when the magnetic sensors (30, 35) provide signals indicating that the coded tooth (26') and the spool have rotated a predetermined number of revolutions in the belt unwinding direction.
|
