Restraint pretensioner with deacceleration mechanism
View Patent ↗Disclosed is a pretensioner for an occupant restraint. The pretensioner is designed to be used in conjunction with an inertial reel that locks the occupant restraint when detecting an adverse event. The pretensioner acts to remove slack in the webbing of the restraint and thereby safely secure the occupant once the reel is locked. The pretensioner described herein includes a rack that is initially held in place by a shear pin. Upon being activated, the rack is forced to a fully extended orientation, whereby the shear pin is severed. A deceleration ramp in included beneath the rack to slowly bring the rack to a stop at the end of the stroke.
1. A pretensioner for tightening an occupant restraint, the pretensioner interconnected to an inertial reel, the inertial reel locking the occupant restraint when provided with a locking signal, the pretensioner comprising:
a pretensioner body having an internal cylindrical bore with proximal and distal ends, a fluid port at the proximal end and an opening at the distal end, a removable end cap frictionally fitted within the opening;
a rack comprising an elongated shaft having proximal and distal ends and upper and lower surfaces, the upper surface portion of the shaft having teeth formed there along, the lower surface of the shaft having a horizontally planar portion and an obtusely angled surface portion adjacent the proximal end, a piston formed at the proximal end of the shaft, a shear pin mounted to the distal end of the shaft, the rack having un-extended and extended orientations;
an initiator and pressure chamber housed in said pretensioner body adjacent the proximal end of the bore, the pressure chamber being perpendicular to the bore and in communication with the fluid port, the initiator having an activated state wherein fluid is delivered into the pressure chamber, through the fluid port, and against the piston, whereby the rack is moved from the un-extended to the extended orientation, movement of the rack to the extended orientation severing the shear pin and ejecting the end cap;
a pinion held on a pinion shaft rotatably supported within the pretensioner body, the pinion shaft being connectable to the inertial locking reel, the pinion being disengaged from the rack with the rack in the un-extended and extended orientations, the pinion engaging the rack as the rack is moved between the un-extended to the extended orientation;
a fixed deceleration ramp positioned within the bore and in slidable contact with the lower surface of the rack, the deceleration ramp having an angled surface in a first orientation, the angled surface of the deceleration ramp interfering with the lower surface of the rack, whereby as the angled surface of the deceleration ramp engages the obtusely angled surface portion of the rack, the rack is slowed prior to reaching the extended orientation and whereby as the rack reaches its extended orientation the fixed deceleration ramp remains in the first orientation and locks the rack in the extended orientation while minimizing bounce back of the rack.
2. A pretensioner for tightening an occupant restraint, the pretensioner comprising:
a pretensioner body having an internal bore with proximal and distal ends, a fluid port at the proximal end;
a rack comprising an elongated shaft having proximal and distal ends and upper and lower surfaces, the upper surface of the shaft having teeth formed there along, the lower surface of the shaft having a horizontally planar portion and a first obtusely angled surface portion depending therefrom adjacent the proximal end, a piston formed at the proximal end of the shaft, the rack having un-extended and extended orientations;
an initiator housed in said pretensioner body adjacent the proximal end of the bore, the initiator having an activated state wherein fluid is delivered against the piston, whereby the rack is moved from the un-extended to the extended orientation;
a pinion held on a pinion shaft rotatably supported within the pretensioner body, the pinion being disengaged from the rack with the rack in the un-extended and extended orientations, the pinion engaging the rack as the rack is moved between the un-extended to the extended orientation;
a fixed deceleration ramp positioned within the bore and in slidable contact with the lower surface of the rack, the deceleration ramp having an angled surface in a first orientation, the angled surface of the deceleration ramp interfering with the lower surface of the rack, whereby as the angled surface of the deceleration ramp engages the first obtusely angled surface portion of the rack, the rack is slowed prior to reaching the extended orientation and whereby as the rack reaches its extended orientation the fixed deceleration ramp remains in the first orientation and locks the rack in the extended orientation while minimizing bounce back of the rack.
3. The pretensioner as described in claim 2 further comprising an opening at the distal end of the bore and wherein a removable cap is fitted over the opening.
4. The pretensioner as described in claim 3 wherein the cap is ejected from the opening upon the rack achieving its extended orientation.
5. The pretensioner as described in claim 2 wherein a pressure chamber is positioned beneath the initiator and wherein fluid from the initiator is delivered downwardly into the chamber.
6. The pretensioner as described in claim 5 wherein the initiator and the pressure chamber are orientated at a 90 degree angle to the bore.
7. The pretensioner as described in claim 2 wherein the deceleration ramp is locked underneath the rack when the rack is in its extended orientation.
8. The pretensioner as described in claim 2 wherein the rack is interconnected to an inertial reel.
9. The pretensioner as described in claim 2 wherein the lower surface of the rack includes a second obtusely angled surface portion, and wherein when the fixed deceleration ramp engages the first obtusely angled surface portion movement of the rack is slowed and when the deceleration ramp engages the second obtusely angled surface portion the movement of the rack is stopped and the rack is locked in the extended orientation by the fixed deceleration ramp and bounce back is minimized.
10. A pretensioner for tightening an occupant restraint, the pretensioner comprising:
a pretensioner body having an internal bore with proximal and distal ends, a fluid port at the proximal end;
a rack comprising an elongated shaft having proximal and distal ends and upper and lower surfaces, the upper surface of the shaft having teeth formed there along, the rack having un-extended and extended orientations;
an initiator housed in said pretensioner body adjacent the proximal end of the bore, the initiator having an activated state wherein fluid is delivered against a piston, whereby the rack is moved from the un-extended to the extended orientation when the initiator is activated;
a pinion held on a pinion shaft rotatably supported within the pretensioner body; a fixed deceleration ramp having a first orientation positioned within the bore and in slidable contact with the lower surface of the rack when the rack is in its un-extended orientation, the deceleration ramp remaining in the first orientation and locking the rack in its extended orientation and minimizing bounce back following activation of the initiator.
11. The pretensioner as described in claim 10 wherein the lower surface of the rack has a horizontally planar portion and a first obtusely angled surface portion depending therefrom.
12. The pretensioner as described in claim 11 wherein as the deceleration ramp engages the first obtusely angled surface portion of the rack, the rack is slowed prior to reaching the extended orientation.
13. The pretensioner as described in claim 11 wherein the lower surface of the rack further includes a second obtusely angled surface portion depending from the first obtusely angled surface portion adjacent the proximal end of the rack, and wherein when the deceleration ramp engages the second obtusely angled surface portion the movement of the rack is stopped.
14. The pretensioner as described in claim 10 wherein a pressure chamber is positioned beneath the initiator and wherein fluid from the initiator is delivered downwardly into the chamber.
15. The pretensioner as described in claim 14 wherein the initiator and the pressure chamber are orientated at a 90 degree angle to the bore.
16. The pretensioner as described in claim 10 further comprising an opening at the distal end of the bore and wherein a removable cap is fitted over the opening.
17. The pretensioner as described in claim 10 wherein the pinion engages the rack.
18. The pretensioner as described in claim 17 wherein the rack includes toothless portions at the proximal and distal ends.
19. The pretensioner as described in claim 18 wherein the pinion is disengaged from the rack when the pinion is positioned over the toothless portions.
20. The pretensioner as described in claim 19 wherein the pinion is interconnected to an inertial reel.