Tension reductive seat belt retractor for automotive safety belt arrangement with enhanced belt retracting performance

摘要

A reductive seat belt retractor for an automotive seat belt arrangement has a belt spool rotatably supported on a housing by a spool shaft which is rotatable with the belt spool in belt extracting and retracting directions. The spool shaft rigidly mounts a first gear for co- rotation therewith. A plurality of second gears are associated with the first gear for transmitting rotational torque therebetween. An internal gear is associated with the first and/or second gears for transmitting rotational torque therebetween, the internal gear being provided greater gear ratio versus the first gear. A ratchet wheel defining a spring receptacle chamber and a locking member associated with the ratchet wheel are provided for establishing and releasing locking of the ratchet wheel for preventing the ratchet wheel from rotating at least in the belt retracting direction. A solenoid is associated with the locking member for establishing locking engagement between the ratchet wheel and the locking member when a seat belt is worn by a passenger, and for releasing the locking engagement when the passenger takes off the seat belt. First and second springs disposed within the chamber are associated to each other in series. A spring force transmitting network includes a first force transmitting network active at unlocked position of the ratchet wheel and a second force transmitting network active at locking position of the ratchet wheel.