Variable sensitivity seat belt retractor

In a seat belt retractor adapted for mounting on a vehicle door and having a belt reel and a reel locking mechanism activated by an inertia mass sensor for locking the reel against belt unwinding rotation in response to a sensed acceleration condition of predetermined level less than the level experienced by the retractor during door opening and closing movement, an improvement for reducing the sensitivity of the inertia mass sensor in the lateral direction of door movement, comprising:

• a pendulum having an inertia mass mounted atop a pedestal, said pedestal having a generally planar foot at the bottom thereof having an elongated elliptical footprint with a major dimension and a minor dimension;
• a pendulum support member carried by the retractor and having a planar support surface located at the bottom of an elongated elliptical well having a major dimension extending laterally of the vehicle and a minor dimension extending longitudinally of the vehicle;
• said pendulum being carried by the pendulum support with the foot of the pendulum standing in the well of the pendulum support member so that the pendulum remains oriented with the major dimension of the foot extending laterally of the vehicle and the minor dimension of the foot oriented longitudinally whereby the locking sensitivity of the retractor is varied between the predetermined level of acceleration in the longitudinal direction and a somewhat higher level of acceleration in the lateral direction of door opening movement so that the retractor is not locked by the level of acceleration experienced during door opening movement.

In a seat belt retractor adapted for mounting on a vehicle door and having a belt reel and a reel locking mechanism activated by an inertia mass sensor for locking the reel against belt unwinding rotation in response to an a sensed acceleration condition of predetermined level less than the level experienced by the retractor during normal door opening movement;

• an improvement for reducing the sensitivity of the inertia mass sensor in the lateral direction of door movement so that the retractor locking mechanism will not lock during normal door opening movement, comprising:
• a pendulum having an inertia mass suspended from a stem, said stem having a generally planar support foot thereof having an elongated elliptical footprint with a major dimension and a minor dimension;
• a pendulum support member carried by the retractor and having a planar support surface located at the bottom of an elongated elliptical well having a major dimension extending laterally of the vehicle and a minor dimension extending longitudinally of the vehicle, said support member having an aperture in the planar support surface for receiving the stem of the pendulum;
• said pendulum being carried by the pendulum support with the foot of the pendulum supported in the well of the pendulum support member so that the pendulum remains oriented with the major dimension of the foot extending laterally of the vehicle and the minor dimension of the foot oriented longitudinally whereby the locking sensitivity of the retractor is varied between the predetermined level of acceleration in the longitudinal direction and a level of acceleration in lateral direction somewhat higher than the predetermined level so that the retractor locking mechanism is not locked by the level of lateral acceleration experienced during door opening movement.