Patent ID: 6532739
Filing Date: 2003-03-18
Classification: B60R,F15B

Abstract:
A pretensioner which rotates a spool of a seat belt retractor to pretension a seat belt in the event of an emergency, comprising:a gas generator; a pipe connected to the gas generator and positioned to receive generated gas; a plurality of balls which are arranged in series in the pipe to be accelerated by the generated gas in a direction away from the gas generator; and wherein the ball which is nearest to the gas generator is a piston which is designed to provide gas-tight seal relative to the wall of the pipe; means for converting the movement of the accelerated balls to a force for rotating the spool, the means including a clutch for coupling the pretensioner to the spool; and a gas release hole formed in the pipe in such a position that before the piston moves the piston is between the hole and the gas generator and when the coupling of the clutch is completed by the movement of the accelerated balls and the piston the hole is located between the gas generator and the piston.