초록 ▼

An adaptive load limiting seat belt retractor particularly adapted for motor vehicle applications. The retractor provides multiple levels of load limiting through the use of a pair of internal torsion bar elements. The torsion bar elements control the tension force on the seat belt webbing during an

An adaptive load limiting seat belt retractor particularly adapted for motor vehicle applications. The retractor provides multiple levels of load limiting through the use of a pair of internal torsion bar elements. The torsion bar elements control the tension force on the seat belt webbing during an impact in a manner which provides desirable crash management characteristics. The retractor can be switched between high and low load limiting modes through activation of a pyrotechnic pretensioner. When the pyrotechnic pretensioner is not activated, the retractor provides a low load level characteristic. Pretensioner activation switches the retractor into a high load level operating condition. A high load limiting level is provided when the pretensioner is not activated if the spindle rotation exceeds a limited level in the low load limiting condition. A degressive load limiting feature may be provided to cause load limiting to begin at a higher level than the high load limiting level, and then step down the high load limiting level.

대표청구항 ▼

1. An adaptive load limiting seat belt retractor for seat belt webbing of a motor vehicle occupant restraint system, comprising: a retractor frame adapted to be mounted to the motor vehicle,a spindle assembly supported for rotation by the retractor frame assembly and having a spindle with a hollow i

1. An adaptive load limiting seat belt retractor for seat belt webbing of a motor vehicle occupant restraint system, comprising: a retractor frame adapted to be mounted to the motor vehicle,a spindle assembly supported for rotation by the retractor frame assembly and having a spindle with a hollow interior and an outer surface adapted for winding the webbing, a first torsion bar and a second torsion bar positioned end to end and at least partially disposed within the spindle hollow interior, the first torsion bar having an end fixed to the spindle, the second torsion bar having an end coupled to a tread head hub, the first and second torsion bars arranged end to end and meeting at a rim, the rim coupled with a pretensioner pinion,a tread head mounted to the retractor frame and engaging the tread head hub to lock the spindle to the frame in response to inertial loads acting on the retractor, and upon locking with the spindle, tension loads acting on the seat belt produce torque on the spindle carried through the first and second torsion bars, which provides a low seat belt load limiting function, anda pretensioner assembly for causing the pinion to rotate the spindle for pretensioning the belt webbing and locking the pinion to the frame with tension loads acting on the seat belt produce torque on the spindle are coupled through the torsion bar rim and pinion and carried by the first torsion bar section, thereby providing a high seat belt load limiting function;a torque transfer tube positioned around at least one of the torsion bars and connected with the torsion bar rim at one end thereof and with the pretensioner pinion at another end thereof; anda connection between the torque tube and the tread head hub enabling limited relative rotation therebetween, and upon the limited relative rotation being exceeded, the torque tube and the tread head hub being rotationally coupled to transfer torque therebetween, whereupon the tension loads acting on the seat belt produce torque on the spindle carried by the first torsion bar, and provide the high seat belt load limiting function. 2. The adaptive load limiting seat belt retractor according to claim 1, further comprising a degressive element coupling the torque tube to the spindle to provide load transfer therebetween until a predetermined torsion load resulting from the tension loads acting on the seat belt is exceeded, whereupon relative rotation between the torque tube and spindle occurs as the first torsion bar is torsionally deformed. 3. The adaptive load limiting seat belt retractor according to claim 1, wherein one of the torque tube and the tread head hub forms a pin and the other of the torque tube or tread head hub forms an arcuate slot with the pin fit in the slot. 4. The adaptive load limiting seat belt retractor according to claim 3, wherein the pin and the arcuate slot permit the relative rotation between the torque tube and the tread head hub up to about 330 degrees. 5. The adaptive load limiting seat belt retractor according to claim 1, wherein the pretensioner assembly is a rotopretensioner having a gas generator, a pretensioner ball tube, pretensioner balls positioned inside the tube, and an enclosure partially surrounding the pinion, and upon activation of the gas generator, gas produced by the gas generator drives the balls into engagement with the pinion, thereby rotating the pinion. 6. The adaptive load limiting seat belt retractor according to claim 5, wherein the pretensioner spindle becomes locked to the retractor frame after activation of the pretensioner assembly. 7. The adaptive load limiting seat belt retractor according to claim 1, wherein the first and second torsion bars are formed by separate torsion bar elements which are joined together by splines. 8. The adaptive load limiting seat belt retractor according to claim 1, wherein the first torsion bar has a higher torsional stiffness than the second torsion bar. 9. An adaptive load limiting seat belt retractor for seat belt webbing of a motor vehicle occupant restraint system, comprising: a retractor frame adapted to be mounted to the motor vehicle,a spindle assembly supported for rotation by the retractor frame and having a spindle with a hollow interior and an outer surface adapted for winding the webbing, a first torsion bar and a second torsion bar positioned end to end and at least partially disposed within the spindle hollow interior, the first torsion bar having an end fixed to the spindle, the second torsion bar having an end coupled to a tread head hub, the first and second torsion bars arranged end to end and meeting at a rim, a torque transfer tube positioned around at least one of the torsion bars and connected with the torsion bar rim at one end thereof and with a pretensioner pinion at another end thereof, the rim coupled with a pretensioner pinion,a tread head mounted to the retractor frame and engaging the tread head hub to lock the spindle to the frame in response to inertial loads acting on the retractor, and upon locking with the spindle, tension loads acting on the seat belt produce torque on the spindle carried through the first and second torsion bars, which provides a low seat belt load limiting function, anda rotopretensioner assembly having a gas generator, a pretensioner ball tube, with pretensioner balls positioned inside the tube, and an enclosure partially surrounding the pinion, upon activation of the gas generator, gas produced by the gas generator drives the balls to engage the pinion, driving the pinion to rotate the spindle and locking the pinion to the frame with the spindle tension loads acting on the seat belt carried by the first torsion bar and the torque transfer tube, thereby providing a high seat belt load limiting function;a connection between the torque tube and the tread head hub enabling limited relative rotation therebetween, and upon the limited relative rotation being exceeded, the torque tube and the tread head hub are rotationally coupled to transfer torque therebetween, whereupon the tension loads acting on the seat belt produce torque on the spindle carried by the first torsion bar, and providing the high seat belt load limiting function. 10. The adaptive load limiting seat belt retractor according to claim 9, further comprising a degressive element coupling the torque tube to the spindle to provide load transfer therebetween until a predetermined torsion load resulting from the tension loads acting on the seat belt is exceeded, whereupon relative rotation between the torque tube and spindle occurs as the first torsion bar is torsionally deformed. 11. The adaptive load limiting seat belt retractor according to claim 9 wherein one of the torque tube or the tread head hub forms a pin and the other of the torque tube or spindle hub forms an arcuate slot with the pin fit in the slot. 12. The adaptive load limiting seat belt retractor according to claim 11 wherein the pin and the arcuate slot permits the relative rotation between the torque tube and the tread head hub up to about 330 degrees. 13. The adaptive load limiting seat belt retractor according to claim 9, wherein the first and second torsion bars are formed by separate torsion bar elements which are joined together by splines. 14. The adaptive load limiting seat belt retractor according to claim 9, wherein the first torsion bar has a higher torsional stiffness than the second torsion bar.