Emergency locking retractor for seat belt assemblies

Abstract

In a seat belt retractor having a reel to which a belt is anchored at one end and which is spring biased pawl is pivotally mounted on a retractor frame for movement into and out of engagement with a pair of ratchet-toothed flanges provided on the reel. Disposed coaxially with the reel are a cam wheel rotatable simultaneously therewith and an inertia wheel rotatable through a predetermined angle relative to the cam wheel. These wheels have on and along their peripheries protuberances which are disposed at a predetermined pitch. During rotation of the reel in a direction of belt extension at relatively low acceleration, the inertia wheel is rotated in synchronism with the cam wheel via a spring. This spring yields, upon a high acceleration being imparted to the reel in the direction of belt extension, to permit the inertia wheel to lag behind the cam wheel by the predetermined angle. The lagging of the inertia wheel behind the cam wheel is sensed by a follower lever associated with the locking pawl, whereupon the locking pawl engages the pair of ratchet-toothed flanges of the reel thereby locking the same against any further rotation in the direction of belt extension. Several embodiments are disclosed.