Patent ID: 7878530

Claim:
A rear-impact airbag apparatus for use in a vehicle, the apparatus comprising: an inflator that ejects gas in response to an impact applied to the vehicle from the rear; and an airbag accommodated in an accommodation portion formed in a rear portion of a roof of the vehicle, wherein, when supplied with gas from the inflator, the airbag pops out of the accommodation portion and is inflated and deployed, wherein a lateral inflatable cell, which guides gas from the inflator to flow outward in a width direction of the vehicle, and a vertical inflatable cell, which guides gas flowing therein from an end of the lateral inflatable cell to flow substantially downward, are defined in the airbag, wherein a gas flowing path cross-sectional area of a boundary between the lateral inflatable cell and the vertical inflatable cell is larger than a gas flowing path cross-sectional area of the lateral inflatable cell, wherein the inflated and deployed airbag has a shape the width of which increases from the top to the bottom, wherein, before being inflated and deployed, the airbag is accommodated in the accommodation portion in a folded up state, in which the airbag is folded along a vertical direction to form an intermediate body having an elongated shape and the intermediate body is then folded at a mountain fold line and a valley fold line defined in each end of the intermediate body, and wherein, prior to inflation and deployment of the airbag, the boundary is located in a folded and layered portion formed by mountain-and-valley-folding the ends of the intermediate body.