Side airbag assembly

1. A restraint system comprising:

a seat defining a vertical axis;

a linear guide adjacent the seat, the linear guide having a base fixed relative to the seat and a lifter moveable relative to the base along the vertical axis; and

an airbag having a mounting connection, the mounting connection being supported by and fixed to the lifter of the linear guide;

wherein the linear guide is telescopic; and

wherein the seat includes a seat bottom having a top and a bottom spaced from the top, the lifter being disposed between the top and the bottom in an undeployed position and a deployed position.

2. The restraint system of claim 1 , wherein the linear guide being configured to restrict movement of the lifter transverse to the vertical axis.

3. The restraint system of claim 1 , further comprising a pyrotechnic actuator supported by the seat and engaged with the lifter, the pyrotechnic actuator positioned to move the lifter upwardly relative to the seat from an undeployed position to a deployed position.

4. The restraint system of claim 3 , further comprising a processor and a memory storing instructions to actuate the pyrotechnic actuator in response to detecting a vehicle impact.

5. The restraint system of claim 1 , wherein the seat includes a seatback defining an occupant seating area, the airbag extends from the lifter along the occupant seating area in an inflated position.

6. The restraint system of claim 1 , further comprising a plurality of external tethers extending from the lifter to the seat.

7. The restraint system of claim 6 , wherein the external tethers extend along the seat bottom and the seatback when the airbag is uninflated.

8. The restraint system of claim 6 , wherein the external tethers are attached to the seat and the lifter, the external tethers being under tension between the seat and the lifter when the airbag is in an inflated position.

9. The restraint system of claim 6 , wherein the airbag in an inflated position is disposed between the external tethers and the seat.

10. The restraint system of claim 6 , wherein the external tethers are a reaction surface for the airbag in an inflated position.

11. The restraint system of claim 6 , wherein the external tethers are fabric and uninflatable.

12. The restraint system of claim 1 , wherein the linear guide is supported by the seat.

13. The restraint system of claim 1 , further comprising a cover supported by the seat, the cover enclosing the lifter and the base.

14. The restraint system of claim 13 , wherein the cover includes a slit disposed adjacent to the airbag, and the airbag extends through the slit in an inflated position.

15. The restraint system of claim 13 , wherein the cover is disposed alongside the seat.

16. The restraint system of claim 13 , further comprising an inflator in fluid communication with the airbag, wherein the cover encloses the inflator.

17. A restraint system comprising:

a seat;

a linear guide adjacent the seat, the linear guide having a base fixed relative to the seat and a lifter moveable relative to the base;

an airbag having a mounting connection, the mounting connection being supported by and fixed to the lifter of the linear guide; and

a cover supported by the seat, the cover enclosing the lifter and the base.

18. A restraint system comprising:

a seat;

a linear guide adjacent the seat and supported by the seat, the linear guide having a base fixed relative to the seat and a lifter moveable relative to the base; and

an airbag having a mounting connection, the mounting connection being supported by and fixed to the lifter of the linear guide;

wherein the linear guide is telescopic.