초록 ▼

A retractor includes a pretensioner whereby increased control and variation over the load limitation characteristics of the retractor are provided. The seat belt and spool are linked to a locking mechanism through a first force limiting element, while the pretensioner is linked to the seat belt and

A retractor includes a pretensioner whereby increased control and variation over the load limitation characteristics of the retractor are provided. The seat belt and spool are linked to a locking mechanism through a first force limiting element, while the pretensioner is linked to the seat belt and spool through a second force limiting element. Both the first and second force limiting elements are employed during a load limiting phase of the retractor.

대표청구항 ▼

The invention claimed is: 1. A retractor for a seat belt restraining system for restraining an occupant of an automobile having a sensor detecting an impact event, the retractor comprising: a spool receiving a portion of the seat belt; a first force limiting element connected to the spool; a lockin

The invention claimed is: 1. A retractor for a seat belt restraining system for restraining an occupant of an automobile having a sensor detecting an impact event, the retractor comprising: a spool receiving a portion of the seat belt; a first force limiting element connected to the spool; a locking mechanism operatively connected to the spool through the first force limiting element; a second force limiting element connected to the spool; a pretensioner having a drive mechanism operatively connected to the spool through the second force limiting element; and the retractor operable in at least two modes upon detection of an impact event including, a first load limiting mode wherein the locking mechanism is activated to limit belt force through the first force limiting element, and a second load limiting mode, wherein the drive mechanism of the pretensioner is activated to retract seat belt onto the spool and blocked to limit force through the second force limiting element, and wherein the locking mechanism is activated to limit belt force through the first force limiting element. 2. The retractor of claim 1, wherein the second load limiting mode includes a pretensioning phase wherein the drive mechanism of the pretensioner rotates the spool, and a load limiting phase wherein the drive mechanism is blocked throughout the entire load limiting phase. 3. The retractor of claim 1, wherein the drive mechanism includes a driven element that, after being driven and rotating the spool, substantially maintains its position throughout the entire impact event. 4. The retractor of claim 1, wherein the second force limiting element absorbs belt force caused by the occupant pressing on the seat belt. 5. The retractor of claim 1, wherein the first load limiting mode provides a low constant load limitation characteristic. 6. The retractor of claim 1, wherein the second load limitation mode provides a high constant load limitation characteristic. 7. The retractor of claim 1, wherein the second load limitation mode provides degressive load limitation. 8. The retractor of claim 1, wherein the first and second force limiting elements are torsion bars that deform under a predetermined load. 9. The retractor of claim 1, wherein the drive mechanism includes a pyrotechnic charge. 10. The retractor of claim 9, wherein the drive mechanism is blocked by maintaining pressure generated by the pyrotechnic charge. 11. The retractor of claim 1, wherein the drive mechanism is an electric motor. 12. The retractor of claim 1, wherein the drive mechanism includes a one-way locking element. 13. The retractor of claim 12, wherein the one-way locking element includes a spring biased lever. 14. The retractor of claim 12, wherein the one-way locking element is activated only upon activation of the drive mechanism of the pretensioner. 15. The retractor of claim 14, wherein the one-way locking element is originally maintained in an unlocked position by a retaining tap, and wherein activation of the drive mechanism causes a moving element to engage the retaining tap and release the one-way locking element to its locked position. 16. A method for restraining an occupant of an automobile having seat belt securing the occupant and a sensor detecting an impact event, and generating a pretension signal, the method comprising: providing a retractor having a pretensioner, a spool, a first force limiting element, a second force limiting element, and a locking mechanism, the spool receiving a portion of the seat belt, the first force limiting element operatively connecting the spool and locking mechanism, the pretensioner having a drive mechanism, the second force limiting element operatively linking the spool and drive mechanism; activating the drive mechanism of the pretensioner based on the pretension signal indicative of an impact event to retract seat belt onto the spool; and maintaining the position of the drive mechanism of the pretensioner throughout the impact event to provide load limitation via the second force limiting element. 17. The method of claim 16, wherein the step of maintaining the position of the drive mechanism includes the second force limiting element absorbing belt force caused by the occupant pressing on the seat belt. 18. The method of claim 16, further comprising the step of activating the locking mechanism to limit belt force through the first load limiting element. 19. The method of claim 16, wherein the step of activating the drive mechanism includes activating a one-way locking element for maintaining the position of the drive mechanism of the pretensioner. 20. A retractor for seat belt restraining system in an automobile having seat belt restraining an occupant and a sensor detecting a potential crash event, the retractor comprising: a spool receiving a portion of the seat belt; a first force limiting element connected to the spool; a locking mechanism operatively connected to the spool through the first force limiting element; a second force limiting element connected to the spool; a pretensioner having a drive mechanism and a driven element operatively connected to the spool through the second force limiting element and structured such that movement of the driven element causes rotation of the spool to tension the seat belt; and the pretensioner including a one-way locking element that is activated only upon initiation of the pretensioner and its drive mechanism, the one-way locking element blocking movement of the driven element of the drive mechanism to prevent rotation of the spool and pay out the seat belt. 21. The retractor of claim 1, wherein the pretensioner includes a driven element responsive to the drive mechanism and structured to cause rotation of the spool to retract the seat belt upon activation of the drive mechanism, and wherein the driven element is blocked after it rotates the spool to limit force through the second force limiting element.