Airbag cushion and mounting therefor

An airbag cushion has a deployment tube connected at its inner end to a backing plate securing an inflator and at its outer end to a cushion-shaping enclosure. The periphery of the cushion-shaping enclosure is attached there about to a boundary wall which extends inward to the backing plate at a location surrounding the inner end of the deployment tube. The boundary wall defines an aspirated-air chamber surrounding the tube. As the tube and cushion-shaping enclosure are inflated, the enclosure pulls the boundary wall out of the canister creating a vacuum in the aspirated-air chamber. A one-way valve in the backing plate passes aspirated air into the aspirated-air chamber. A port connects the cushion-shaping enclosure to the aspirated-air chamber to pressurize the aspirated-air chamber at the end of inflation. The one-way valve blocks escape of the pressure.