Seatback supported airbag and seatbelt webbing

1. An assembly comprising:

a vehicle seat having a seat bottom and a seatback supported by the seat bottom;

an airbag supported by the seatback, the airbag being inflatable to an inflated position;

a seatbelt webbing extending from the seatback to the airbag, the seatbelt webbing being between the airbag and the seatback in the inflated position;

a pyrotechnic device supported by and fixed in position relative to the seat bottom and operatively coupled to the airbag to pull the airbag downwardly toward the seat bottom; and

a retractor supported by and fixed in position relative to the seatback, the seatbelt webbing being retractably coupled to the retractor so that the webbing is retractable into the retractor and the retractor prevents extension of the seatbelt webbing from the retractor.

2. The assembly of claim 1 , wherein the airbag includes a main chamber, a first tubular chamber, and a second tubular chamber, the main chamber being between the first tubular chamber and the second tubular chamber.

3. The assembly of claim 2 , wherein the seatback defines a first bolster and a second bolster spaced cross-seat from the first bolster, the first tubular chamber extending along the first bolster in the inflated position and the second tubular chamber extending along the second bolster.

4. The assembly of claim 2 , further comprising an inflator supported by the seatback, the inflator being in fluid communication with the main chamber, the first tubular chamber, and the second tubular chamber.

5. The assembly of claim 2 , wherein the vehicle seat defines an occupant seating area, the occupant seating area being between the first tubular chamber and the second tubular chamber when the airbag is in the inflated position.

6. The assembly of claim 1 , wherein the seatback defines a first bolster and a second bolster spaced cross-seat from the first bolster, the airbag extends from the first bolster to the second bolster in the inflated position.

7. The assembly of claim 1 , wherein the seatbelt webbing includes a lap portion elongated in a cross-seat direction and a pair of shoulder portions extending from the seatback to the lap portion, the shoulder portions being spaced cross-seat from each other.

8. The assembly of claim 7 , wherein the vehicle seat includes a head restraint supported by and extending upwardly from the seatback, the head restraint being between the shoulder portions.

9. The assembly of claim 7 , wherein:

the airbag includes a first tubular chamber and a second tubular chamber spaced cross-seat from the first tubular portion; and

the lap portion extending from the first tubular chamber to the second tubular chamber.

10. The assembly of claim 7 , wherein, when the airbag is in the inflated position, the lap portion is designed to extend across a lap of an occupant of the vehicle seat and the shoulder portions are designed to extend across shoulders of the occupant.

11. The assembly of claim 1 , further comprising a tether extending from the pyrotechnic device to the airbag, the tether being retractable by the pyrotechnic device.

12. The assembly of claim 1 , further comprising a second pyrotechnic device supported by the seat bottom and spaced cross-seat from the pyrotechnic device.

13. The assembly of claim 12 , further comprising a first tether extending from the pyrotechnic device to the airbag and a second tether extending from the second pyrotechnic device to the airbag, the first tether and the second tether being retractable by the pyrotechnic devices.

14. The assembly of claim 1 , wherein:

the vehicle seat defines an occupant seating area, the occupant seating area being between the airbag and the seatback when the airbag is in the inflated position; and

the occupant seating area is between the seatbelt webbing and the seatback when the airbag is in the inflated position.

15. The assembly of claim 14 , wherein the seatbelt webbing is between the airbag and the occupant seating area when the airbag is in the inflated position.

16. The assembly of claim 1 , wherein the pyrotechnic device is designed to pull the seatbelt webbing across an occupant of the vehicle seat when the airbag is in the inflated position.

17. The assembly of claim 1 , wherein the seatbelt webbing extends from an upper end of the seatback to a bottom end of the airbag when the airbag is in the inflated position.

18. The assembly of claim 17 , wherein the seatbelt webbing is unattached to the airbag between the upper end of the seatback and the bottom end the airbag.

19. An assembly comprising:

a vehicle seat having a seat bottom and a seatback supported by the seat bottom;

an airbag supported by the seatback, the airbag being inflatable to an inflated position;

a seatbelt webbing extending from the seatback to the airbag, the seatbelt webbing being between the airbag and the seatback in the inflated position; and

a pyrotechnic device supported by the seat bottom and operatively coupled to the airbag;

the seatbelt webbing extending from an upper end of the seatback to a bottom end of the airbag when the airbag is in the inflated position; and

the seatbelt webbing being unattached to the airbag between the upper end of the seatback and the bottom end the airbag.

20. An assembly comprising:

a vehicle seat having a seat bottom and a seatback supported by the seat bottom;

an airbag supported by the seatback, the airbag being inflatable to an inflated position;

a seatbelt webbing extending from the seatback to the airbag, the seatbelt webbing being between the airbag and the seatback in the inflated position; and

a pyrotechnic device supported by the seat bottom and operatively coupled to the airbag;

the seatbelt webbing including a lap portion elongated in a cross-seat direction and a pair of shoulder portions extending from the seatback to the lap portion, the shoulder portions being spaced cross-seat from each other.