Emergency locking retractor

A vehicle seat belt retractor comprising:

• a reel shaft;
• an elongated belt section having one end fixed to the reel shaft;
• a locking member movable between a first position wherein it allows rotation of the reel in a belt extending direction and a second position wherein it locks the reel against rotation in a belt extending direction;
• first means for connecting the reel shaft to the locking member so as to move said locking member from its first position to its second position when the rate of rotational acceleration of the reel in a belt extending direction exceeds a predetermined level, said first means comprising a flywheel supported on the reel shaft for rotation about the reel shaft, second means connected between the flywheel and the reel shaft and operative to urge the flywheel toward rotation in the belt extending direction when the reel shaft rotates in the belt extending direction;
• and third means, separate from said locking member, supported at least partially on a portion of the reel shaft and movable toward the periphery of the reel shaft upon slippage of the flywheel relative to the reel shaft, whereby locking forces to prevent rotation of the reel shaft are exerted on locking member, but not on said separate locking dog.

A seat belt retractor comprising:

• a reel shaft to which one end of a seat belt is fixed;
• a circular ratchet fixed to the reel shaft;
• a locking pawl movable between a first position wherein it allows rotation of the reel shaft in a belt extending direction and a second position wherein it engages said ratchet to prevent rotation of the reel shaft in the belt extending direction;
• and a first mechanism for locking said reel shaft in response to rotational acceleration of said reel shaft, said first mechanism comprising:
• a cylindrical section of said reel shaft, said cylindrical section having a face;
• a flywheel rotatably supported on the reel shaft for rotation thereon, said flywheel having a surface disposed adjacent to said face of said cylindrical section of said reel shaft;
• a spring supported on said face of said cylindrical section, said spring disposed between said cylindrical section and the flywheel surface, means projecting from said flywheel to said spring so as to urge the flywheel to rotate with the reel shaft when the reel shaft rotates in such a direction as to extend the belt;
• and actuator means including a locking dog separate from said locking pawl and adapted to be coupled to the reel shaft and to the flywheel and operative to urge said locking pawl into its second position upon the occurrence of rotational acceleration of the reel shaft in the belt extending direction, whereby locking forces to prevent rotation of the reel shaft are exerted on said locking pawl, but not on said separate locking dog, thereby enabling said locking dog to be relatively light in weight in comparison to said locking pawl to avoid unbalancing said flywheel;
• and wherein:
• said actuator means for moving the locking pawl into its second position upon slippage of the flywheel relative to the reel shaft further comprises:
• an actuator member, and a biasing means;
• said actuator member supported for motion between a first position wherein it does not engage said locking pawl and a second position wherein it engages said locking pawl;
• said face of said cyclindrical section having an arcuate groove;
• said spring being a spirally wound compression spring disposed in said arcuate groove;
• said biasing means biasing said actuator member towards its first position;
• said locking dog supported between said flywheel and said cylindrical section of said reel shaft and operative to couple the reel shaft to the actuator member so as to move the actuator member into engagement with the locking pawl upon slippage of the flywheel relative to the reel shaft;
• said actuator member has an internal toothed ratchet and an actuator arm, said internal toothed ratchet being disposed circumferentially about the reel shaft and overlying at least a part of the flywheel and the cylindrical section of the reel shaft;
• and the dog contacts said ratchet surface upon slippage of the flywheel relative to the reel shaft causing said actuator arm to move the locking pawl into its second position;
• and
• said internal toothed ratchet of the actuator member has the same number of teeth as the circular ratchet fixed to the reel shaft so that the locking pawl moves into engagement with the ratchet fixed to the reel shaft at the same angle relative to the ratchet teeth and independently of the rotational position at which the dog moves into engagement with the actuator member.