Side airbag assembly

An inflatable airbag assembly comprising:

• an inflatable airbag cushion to receive inflation gas from an inflator and to deploy from a packaged state within a seatback of a seat of a vehicle to a deployed state extending forward from a side of the seatback, the inflatable airbag cushion to be positioned, in the deployed state, laterally adjacent to a vehicle seating position, the inflatable airbag cushion comprising:
• a low pressure chamber to be inflated by the inflation gas to a first pressure and to be positioned, in the deployed state, to receive a torso of an occupant moving in a direction transverse to a longitudinal axis of the vehicle;
• and
• a high pressure chamber to be inflated by the inflation gas to a second pressure greater than the first pressure and to be positioned, in the deployed state, to receive a shoulder of an occupant at an upper portion of the high pressure chamber and receive a pelvis of an occupant at a lower portion of the high pressure chamber as the occupant moves in a direction transverse to a longitudinal axis of the vehicle,
• wherein the high pressure chamber is disposed within the low pressure chamber, and is coextensive with a rearward portion, an upward portion, and a lower portion of the low pressure chamber.