Seat belt restraint system

摘要

A seat belt restraint system is provided including a retractor and an optical inertia sensor therefor. The optical inertia has a sensor body with a light emitter and detector recessed in bores therein. A frame support having inclined walls with a base opening at the bottom of the walls support an inertia ball so that it is positioned at the opening to reflect light from the emitter to the detector when vehicle accelerations are within a predetermined range. The inertia sensor is incorporated into circuitry which controls a locking mechanism, e.g. solenoid, at the retractor so that when the detector is sensing light, the retractor stays unlocked. During excessive vehicle acceleration, such as brought on during accident conditions, the ball will roll along the wall so it no longer reflects light from the emitter breaking optical communication between the emitter and detector and locking the retractor. The optical inertia sensor is advantageous in that it uses very few moving parts in contrast to mechanical remote sensors and avoids the reliability problems faced by switch contacts in prior inertia sensors. In addition, the sensor body including the emitter and detector is a commercially available portion of the sensor which utilizes well proven optical components for good reliability in sensor operation and lower costs in fabricating the present sensor.