초록 ▼

An air bag (12) includes at least one tether ( 44) and an inflation fluid source (14) having two modes of operation. In the first mode of operation, the inflation fluid source ( 14) is activated to provide a first inflation fluid pressure in the air bag (12). In the second mode of operation, the inf

An air bag (12) includes at least one tether ( 44) and an inflation fluid source (14) having two modes of operation. In the first mode of operation, the inflation fluid source ( 14) is activated to provide a first inflation fluid pressure in the air bag (12). In the second mode of operation, the inflation fluid source (14) is activated to provide a second inflation fluid pressure in the air bag (12) higher than the first pressure. The tether (44), which helps to control the shape of the air bag ( 12), tears in response to the second inflation fluid pressure in the air bag.

대표청구항 ▼

The invention claimed is: 1. A vehicle occupant safety apparatus comprising: an inflatable vehicle occupant protection device for, when inflated, helping to protect an occupant of a vehicle; at least one tether for helping to control the shape of said inflatable vehicle occupant protection device w

The invention claimed is: 1. A vehicle occupant safety apparatus comprising: an inflatable vehicle occupant protection device for, when inflated, helping to protect an occupant of a vehicle; at least one tether for helping to control the shape of said inflatable vehicle occupant protection device when said inflatable vehicle occupant protection device is inflating; an inflation fluid source having two modes of operation, in the first mode of operation, said inflation fluid source is activated to provide inflation fluid to increase an inflation fluid pressure in said inflatable vehicle occupant protection device to a first inflation fluid pressure, in the second mode of operation, said inflation fluid source is activated to provide inflation fluid to increase said inflation fluid pressure in said inflatable vehicle occupant protection device to a second inflation fluid pressure that is higher than said first inflation fluid pressure, said tether remaining intact in response to said first inflation fluid pressure in said inflatable vehicle occupant protection device, said tether also remaining intact as said inflation pressure increases above said first inflation fluid pressure toward said second inflation fluid pressure; said tether releasing in response to said inflation fluid pressure in said inflatable vehicle occupant protection device reaching said second inflation fluid pressure. 2. The apparatus according to claim 1 wherein said inflation fluid source is a dual stage inflator having two separately actuatable igniters, and wherein a first one of said two separately actuatable igniters is activated in said first mode of operation and both of said actuatable igniters are activated in said second mode of operation. 3. The apparatus according to claim 2 wherein said inflation fluid source includes vehicle electronic circuitry for delaying activation of said second one of said separately actuatable igniters until after said first one of said separately actuatable igniters is activated. 4. The apparatus according to claim 1 wherein said inflation fluid source includes a single stage inflator and a vent opening for enabling a venting of a portion of said inflation fluid away from said inflatable vehicle occupant protection device. 5. The apparatus according to claim 4 wherein said inflation fluid source includes an actuatable door selectively movable from a first location adjacent said vent opening in which said vent opening is uncovered and a portion of said inflation fluid is vented away from said inflatable vehicle occupant protection device to a second location overlying said vent opening in which said vent opening is covered and said inflation fluid is blocked from venting away from said inflatable vehicle occupant protection device through said vent opening. 6. The apparatus according to claim 5 wherein said single stage inflator is activated and said vent opening is uncovered in said first mode of operation of said inflation fluid source and said single stage inflator is activated and said vent opening is covered in said second mode of operation of said inflation fluid source. 7. The apparatus according to claim 6 wherein said inflation fluid source includes vehicle electronic circuitry for delaying activation of said actuatable door to cover said vent opening until after the single stage inflator is activated. 8. The apparatus according to claim 5 wherein said first inflation pressure is provided by activation of said single stage inflator and simultaneously venting through said vent opening a portion of said inflation fluid away from said inflatable vehicle occupant protection device. 9. The apparatus according to claim 8 wherein said second inflation pressure is provided by blocking said inflation fluid generated by said first mode of operation of said inflation fluid source from venting through said vent opening away from said inflatable vehicle occupant protection device as a result of said actuatable door moving to said second location. 10. The apparatus according to claim 1 wherein said tether has a first length when intact and a second length, longer than said first length, when released. 11. The apparatus according to claim 1 wherein said inflatable occupant protection device is made of fabric material and includes a back wall defining an opening into which said inflation fluid source partially extends and a front wall opposite the back wall, the front and back walls defining an interior chamber into which said inflation fluid flows. 12. The apparatus according to claim 11 wherein said tether comprises a piece of elongate fabric material having first and second opposite facing surfaces and first and second terminal ends. 13. The apparatus according to claim 12 wherein said first terminal end of said tether is fixed to said front wall and said second terminal end of said tether is fixed relative to said back wall. 14. The apparatus according to claim 10 wherein said tether includes at least one tear stitch which tears in response to said second inflation fluid pressure in said inflatable vehicle occupant protection device, said tear stitch extending across a width of said tether, and said tether releasing to lengthen from said first length to said second length in response to said tear stitch tearing. 15. The apparatus according to claim 14, wherein said tether lengthens to enable the shape of the inflated inflatable vehicle occupant protection device to change. 16. The apparatus according to claim 14 wherein said tear stitch is formed by a thread that secures together longitudinally spaced portions of said tether. 17. The apparatus according to claim 14 wherein said tear stitch is located on a separate tear strap that is permanently sewn to said tether, said tear strap having a portion with a narrowed width that is adapted to remain intact when the first inflation fluid pressure is provided to the inflatable vehicle occupant protection device and is adapted to tear when the second inflation fluid pressure is provided to the inflatable vehicle occupant protection device. 18. The apparatus according to claim 14 wherein said tether, when in said first length, includes a portion of said material gathered together and forming a loop and secured by said tear stitch. 19. The apparatus according to claim 14 wherein a plurality of tethers are coupled together with a single tear stitch so that the plurality of tethers lengthen in response to said single tear stitch tearing. 20. A vehicle occupant safety apparatus comprising: an inflatable vehicle occupant protection device for, when inflated, helping to protect an occupant of a vehicle; at least one tether for helping to control the shape of said inflatable vehicle occupant protection device when said inflatable vehicle occupant protection device is inflating; an inflation fluid source including separate first and second combustion chambers, said first and second combustion chambers including material that is ignitable to generate inflation fluid, a first igniter associated with said first combustion chamber and actuatable for igniting said material of said first combustion chamber, a second igniter associated with said second combustion chamber and actuatable for igniting said material of said second combustion chamber, said inflation fluid source having two modes of operation, in the first mode of operation, only said first igniter is actuated to ignite the material of said first combustion chamber, inflation fluid generated in the first mode of operation increasing an inflation fluid pressure in said inflatable vehicle occupant protection device to a first inflation fluid pressure, in the second mode of operation, both said first and second igniters being actuated to ignite the material of both the first and second combustion chambers, inflation fluid generated in the second mode of operation increasing said inflation fluid pressure in said inflatable vehicle occupant protection device to a second inflation fluid pressure that is higher than said first inflation fluid pressure, said tether remaining intact in response to said first inflation fluid pressure in said inflatable vehicle occupant protection device, said tether also remaining intact as said inflation pressure increases above said first inflation fluid pressure toward said second inflation fluid pressure; said tether releasing in response to said inflation fluid pressure in said inflatable vehicle occupant protection device reaching said second inflation fluid pressure.