Patent ID: 8297709

Claim:
A seat belt retractor for a seat belt, comprising: a spool for winding the seatbelt, having a groove thereon; a first seat belt load limiting mechanism for limiting load applied on the seat belt in an emergency; a second seat belt load limiting mechanism for limiting the load applied to said seat belt when a predetermined condition according to an emergency situation in the emergency is satisfied, the second seat belt load limiting mechanism having an energy absorbing member for absorbing energy applied to the seat belt, and a supporting member supporting the energy absorbing member and being disposed coaxially with said spool and rotatable relative to said spool and having another groove thereon; a driving member for actuating said second seat belt load limiting mechanism; a controller for controlling said driving member, electrically connected with the driving member; a locking mechanism having a locking member rotating together with said spool by transmission of rotation of said spool via the first seat belt load limiting mechanism during a non emergency situation, and being prevented from rotating in a seatbelt withdrawing direction in the emergency, wherein the energy absorbing member is disposed between said locking member and said supporting member and is deformed by the rotation of said spool in the seat belt withdrawing direction to absorb the energy applied to the seat belt when the locking member is actuated in the emergency to prevent rotation of the locking member in the seatbelt withdrawing direction; a stopper slidably fitted in the groove of the spool and the another groove of the supporting member; and a stopper operating member operating the stopper, wherein when said predetermined condition is satisfied, the controller does not actuate the driving member so that said second seat belt load limiting mechanism is actuated, wherein when said predetermined condition is not satisfied, the controller actuates said second seat belt load limiting mechanism by actuating said driving member, and wherein when said locking member is prevented from rotating in the seat belt withdrawing direction so that said spool rotates in the seat belt withdrawing direction relative to said locking member, the load applied on said seat belt is limited by at least said first seat belt load limiting mechanism.