Seat belt retractor

Abstract

A seat belt retractor including a spool for winding up a seat belt; and a locking mechanism having a locking member that rotates together with the spool in the normal state, but is prevented from rotating in a belt withdrawing direction in the event of an emergency, generating a rotational difference relative to the spool. The spool further including an energy absorbing pin that is disposed on the spool and the locking member to limit the load applied to the seat belt when the rotational difference is generated between the spool and the locking member. The energy absorbing pin has a shaft portion that is fitted in a hole of the spool and a head portion that is in contact with the locking member. The head portion comprises a curved contact surface to be in contact with the locking member.

1 . A seat belt retractor comprising:
 a spool for winding up a seat belt;   a locking mechanism having a locking member that rotates together with the spool in the normal state, but is prevented from rotating in a belt withdrawing direction in the event of an emergency, generating a rotational difference relative to the spool; and   an energy absorbing pin that is disposed on the spool and the locking member to limit the load applied to the seat belt when the rotational difference is generated between the spool and the locking member,   wherein the energy absorbing pin has a shaft portion that is fitted in a hole of the spool and a head portion that is in contact with the locking member, and   wherein the head portion comprises a curved contact surface to be in contact with the locking member.   
   
   
       2 . A seat belt retractor as claimed in  claim 1 , wherein the rotation of the spool is transmitted to the locking member via the torsion bar. 
   
   
       3 . A seat belt retractor as claimed in  claim 1 , wherein the curved contact surface of the head portion is formed into a spherical shape. 
   
   
       4 . A seat belt retractor as claimed in  claim 1 , wherein the head portion is formed into a rod-like shape, and the curved contact surface of the head portion is formed to have an arc or elliptical arc cross section in a direction perpendicular to the longitudinal direction of the head portion, and
 wherein the head portion is in contact with the locking member such that the longitudinal direction of the head portion extends in a radial direction or substantially radial direction of the locking member.   
   
   
       5 . A seat belt apparatus comprising:
 a seat belt retractor for winding up a seat belt;   a tongue slidably supported by the seat belt withdrawn from the seat belt retractor; and   a buckle to which the tongue can be detachably latched,   wherein in the event of an emergency, the seat belt is prevented from being withdrawn by the seat belt retractor so that the seat belt apparatus restrains an occupant;   wherein the seat belt retractor comprises a spool for winding up a seat belt and a locking mechanism having a locking member that rotates together with the spool in the normal state, but is prevented from rotating in a belt withdrawing direction in the event of an emergency, generating a rotational difference relative to the spool, and an energy absorbing pin that is disposed on the spool and the locking member to limit the load applied to the seat belt when the rotational difference is generated between the spool and the locking member;   wherein the energy absorbing pin has a shaft portion that is fitted in a hole of the spool and a head portion that is in contact with the locking member, and wherein the head portion comprises a curved contact surface positioned to be in contact with the locking member.   
   
   
       6 . The apparatus of  claim 5 , wherein the curved contact surface of the head portion is formed into a spherical shape. 
   
   
       7 . The apparatus of  claim 5 , wherein the head portion is formed into a rod-like shape, and the curved contact surface of the head portion is formed to have an arc or elliptical arc cross section in a direction perpendicular to the longitudinal direction of the head portion, and wherein the head portion is in contact with the locking member such that the longitudinal direction of the head portion extends in a radial direction or substantially radial direction of the locking member. 
   
   
       8 . A seat belt apparatus comprising:
 a tongue connected to a seat belt, wherein the tongue is configured to be releasably connected to a buckle; and wherein in the event of a condition involving the vehicle, the retractor prevents the seat belt from being withdrawn;   a seat belt retractor for winding up the seat belt, wherein the retractor includes a spool for winding up a seat belt and a locking member that normally rotates together with the spool; wherein the locking member is prevented from rotating in a belt withdrawing direction in the event of an emergency, thereby generating a rotational difference between the locking member and the spool;   wherein the retractor includes an energy absorbing pin configured to limit the load applied to the seat belt when the rotational difference is generated between the spool and the locking member, the pin including a shaft portion fitted in a hole of the spool and a head portion in contact with the locking member, and wherein the head portion includes a curved contact surface positioned to be in contact with the locking member.