Seat belt take-up device provided with an emergency-locking mechanism

A seat belt retractor for use in a vehicle, the retractor including a housing, a webbing take-up shaft journalled in the housing, the shaft being biased in a webbing retracting direction, and an emergency-locking mechanism comprising:

• a rotatable member supported on said shaft in a manner permitting relative rotation between said member and said shaft;
• a support member non-rotatably supported on said shaft in axially adjacent relationship to said rotatable member;
• a first pawl member associated with said support member for movement between a lock position and a normal non-lock position, said first pawl member being biased toward said normal non-lock position;
• engaging means on said rotatable member for displacing said first pawl member from said normal non-lock position to said lock position responsive to relative rotation occurring between said rotatable member and said shaft;
• first lock means associated with said housing for engaging said first pawl member when said first pawl member is displaced into said lock position, thereby restraining said first pawl member and arresting rotation of said support member and said shaft;
• a second pawl member supported on said rotatable member for movement between a lock position and a normal non-lock position;
• means biasing said second pawl member to its normal non-lock position;
• means for providing rotation of said rotatable member with said shaft when said shaft is rotated from rest in a webbing draw-out direction;
• an inertia member rotatably supported on said shaft for engagement with said second pawl member, said inertia member being displaceable relative to said shaft by inertial force from a normal first position to a second position responsive to an angular acceleration of said shaft in the webbing draw-out direction above a predetermined value, displacement of said inertia member from said first position to said second position effecting movement of said second pawl member from its normal non-lock position to its lock position;
• and
• second lock means associated with said housing for engaging said second pawl member when said second pawl member is displaced to its lock position, so as to arrest said second pawl member and said rotatable member, thereby establishing relative rotation between said rotatable member and said shaft effective for displacing said first pawl member from its non-lock to its lock position whereby said first pawl member engages said first lock means to arrest the rotation of said shaft.