초록 ▼

An improved pretensioner which achieves more stable operation and reduction in power loss. The pretensioner includes a gas generator, a pipe containing a plurality of balls and a piston, and a clutch for connecting the pretensioner to a spool for a seat belt. A gas release hole is formed in the pipe

An improved pretensioner which achieves more stable operation and reduction in power loss. The pretensioner includes a gas generator, a pipe containing a plurality of balls and a piston, and a clutch for connecting the pretensioner to a spool for a seat belt. A gas release hole is formed in the pipe in such a position that before the piston moves the hole is between the piston and the first ball and when the coupling of the clutch is completed by the movement of the accelerated balls and the hole is located between the gas generator and the piston.

대표청구항 ▼

1. 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 b

1. 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. 2. The pretensioner of claim 1, wherein the means for converting includes a ring gear having external teeth for receiving at least one of the plurality of balls. 3. The pretensioner of claim 2, wherein the ring gear includes internal teeth for engaging a pinion connected to the spool. 4. The pretensioner of claim 3, further comprising pins preventing that prevent the ring gear from engaging the pinion prior to activation of the gas generator. 5. A seat belt pretensioner comprising a plurality of balls positioned in a pipe connected to a gas generator configured so that when generated gas enters the pipe the balls are accelerated toward a clutch mechanism for converting the movement of the balls into rotation of a spool for a seat belt, the pipe including a hole in a wall positioned so that before the balls move the hole is sealed off from generated gas by the ball closest to the gas generator, and when the clutch mechanism begins to effect rotation of the spool the hole is located between the gas generator and the ball closest to the gas generator thereby allowing gas to escape. 6. The pretensioner of claim 5, wherein the ball closest to the gas generator is a piston providing a gas tight seal relative to an interior wall of the pipe. 7. A gas release mechanism for a seat belt pretensioner including a gas generator connected to a pipe having a plurality of balls, the mechanism comprising a hole in the pipe positioned so that before the balls move due to the generated gas the hole is isolated from the gas generator by one of the balls and when pretensioning of the seat belt begins the hole is located between the gas generator and the ball closest to the gas generator thereby releasing gas out of the pipe. 8. The gas release mechanism of claim 7, wherein the ball closest to the gas generator provides a gas tight seal with the pipe to thereby isolate the hole from the gas generator.