Inertia sensitive seat hinge mechanism

Claim 1

In an inertia sensitive seat hinge mechanism for supporting a seat back and a seat bottom which permits said seat back to be rotated relative to said seat bottom under normal operating conditions but which restricts rotation of said seat back when said hinge mechanism is exposed to an acceleration above a predetermined level in a predetermined direction, said seat hinge of the type having an upper hinge structure for supporting said seat back and a lower hinge structure for supporting said seat bottom, said upper hinge structure rotatable with respect to said lower hinge structure about a pivot pin, an inertia sensing means comprising: quadrant means operatively connected to said lower hinge structure for defining a stop surface and an actuator biasing surface spaced from said stop surface, an inertia sensitive actuator in the form of a generally straight elongated lever, said actuator defining pivot means adjacent one end thereof, engagement means at the other end thereof, and a projecting finger in close proximity with said pivot means, said pivot means located vertically below and horizontally displaced from said lower hinge structure pivot pin, said actuator mounted for limited rotation such that the center of gravity of said actuator is vertically above and horizontally displaced from said pivot means and said actuator being mounted relative to said quadrant means such that when said seat back is in a folded rearward position, said quadrant actuator biasing surface acts on said projecting finger portion to bias said actuator engagement means to a position of engagment with said stop surface and wherein when said seat back is rotated from said folded rearward position, said actuator biasing surface relieves said bias to permit said actuator engagment means to move out of engagment with said stop surface due to gravity or to remain in said position of engagment due to the influence of said acceleration on said actuator.