Seat belt retraction apparatus with remote inertia sensor

Abstract

Seat belt retraction apparatus including a seat belt retractor mechanism including a reel about which the strap of a seat belt is wound and which carries ratchet wheels. The retractor mechanism is adapted to take up and let out the strap and is provided with an inertia weight locking mechanism to lock the reel against paying out the strap. The retractor mechanism is for mounting in a vehical door and the inertia locking mechanism will not lock the reel at a lower force level such as 0.7G, when the door is swung. However, the retractor mechanism will operate at this lower 0.7G level to lock the reel against belt pay out when the vehicle chassis decelerates at a 0.7G level as at the time of an accident. Preferably, an inertia operable switch is located on the vehicle chassis but at a location not effected by the swinging of the vehicle door. A magnetic force holds the inertia weight locking mechanism against locking as the door is swung at the lower force level of 0.7G and in a range up to 2.4G at which time the magnetic force is overcome. At the time of an accident at the lower force level of 0.7G, the inertia switch operates an electromagnetic device in opposite to the permanent magnetic field so that inertia weight locking mechanism may lock the reel at this lower force level.