Seat belt retractor with dual sensitivity

摘要

A seat belt retractor (12) has a web-sensitive locking mechanism (100) including a primary inertia member (112) which lags rotation of the retractor spool (32) upon acceleration of the spool (32) at a rate above a first predetermined rate. A lock bar (36) blocks rotation of the spool (32) in the unwinding direction when the primary inertia member (112) lags rotation of the spool (32). The retractor (12) also has a sensitivity adjusting mechanism (110) including a secondary inertia member (172). The secondary inertia member (172) has a loading condition in which its mass is applied to the primary inertia member (112) effectively to increase the inertia of the primary inertia member (112). The secondary inertia member (172) is switched into and out of the loading condition in response to rotation of the spool (32). This allows the retractor (12) to provide a low level of webbing sensitivity for the purpose of rapidly donning the seat belt webbing (20) and to provide a high level of webbing sensitivity for locking the retractor (12) in the event of a vehicle collision. The retractor (12) can also be mounted at any angle of inclination, and if mounted in an integrated seat, the retractor (12) will function at any seat back recline angle or yaw angle.