Tension eliminator for a vehicle safety belt retractor

Abstract

A safety belt retractor mechanism for vehicle passengers is described which has an apparatus for selectively relieving belt retractive tension on the passenger. The apparatus may be either manually or automatically engaged at a first extensive position of the belt corresponding to the buckled up position such that, for a single extractive movement of the belt by a first predetermined amount of 'slack', the belt is locked against further retractive movement below that position, thereby relieving the retractive tension of the belt on the wearer. Further extensive and retractive movements of the belt beyond the tensionless position and less than a second predetermined amount, such as would result from passenger forward movements to reach controls, etc., result in normal retractive tension in the belt against the passenger until the passenger returns to the buckled up position. The apparatus then 'remembers' this position and restores the slack to the wearer. Upon extractive movements of the belt greater than the second predetermined amount, or upon manual or automatic disengagement of the tensionless mode, the retractive tension of the belt below the slack position is restored until again reset by the passenger. The apparatus is distinctive in its use of a Geneva mechanism to drive a memory disk having a pair of cams on its surface at a reduced rate through a frictional clutch to operate a locking pawl cooperating with a ratchet disk attached to the spool of the belt retractor to lock and unlock the spool at the appropriate positions. A control arm indexes the memory disk relative to the locking positions and the Geneva mechanism permits significantly increased extensive movements of the passenger beyond the slack position without unlocking the mechanism, as well as increased accuracy of control over the belt slack and unlocking positions.