Compact seat belt retractor

Abstract

A belt reel has a reel shaft journaled on the side walls of a retractor frame and a belt spool attached to the reel shaft in radially spaced relation therefrom by round plates which define an annular space between the reel shaft and the spool and opening outwardly toward the frame side walls. An actuator is pivotally mounted on the end of the reel shaft between the sprocket and frame side wall and depends into proximity with a lock bar to move the lock bar into engagement with a reel sprocket upon rotary movement of the actuator. An acceleration sensing mechanism situated within the annular space is cammed axially to drive couple the reel with the actuator in response to a sensed condition of acceleration so that the actuator is rotated and engages the lock bar with the sprocket. The sensing mechanism may be a flywheel drive coupled with the reel for unitary rotation therewith until belt unwinding rotary acceleration causes the flywheel to lag behind rotation of the reel so that a cam thrusts the flywheel axially into engagement with the actuator. The acceleration sensing mechanism may also be a flyweight drive coupled to the reel for rotation therewith but movable axially along the shaft in response to a deceleration of the vehicle so that the flywheel engages with and rotates the actuator to engage the lock bar with the sprocket.