Patent ID: 7303207

Claim:
An airbag as part of an airbag device mountable on vehicle, the airbag developing and inflating with inflation gas from folded and housed state for protecting a target object of protection with cushioning property thereof when contacting with the target object, the airbag comprising: a bag-shaped circumferential wall; an upstream side base cloth as constituent part of the circumferential wall, the upstream side base cloth being located in upstream side of inflation gas; a downstream side base cloth as constituent part of the circumferential wall, the downstream side base cloth being located in downstream side of inflation gas; and a lap portion formed by superposing a terminal portion of the downstream side base cloth on a terminal portion of the upstream side base cloth, and by joining the terminal portions to each other at both ends of the terminal portions in a direction extending along edges of the terminal portions, whereby the terminal portion of the upstream side base cloth is masked from surface of the airbag, wherein: the lap portion comprises a communication port between joined portions of the upstream side base cloth and the downstream side base cloth and between the terminal portions of the upstream side base cloth and the downstream side base cloth, the port communicating inside and outside of the airbag, whereby: in the course of unfolding and inflation of the airbag, the inflation gas flowing toward the downstream side base cloth from the upstream side base cloth in the lap portion sucks air into the airbag from outside via the communication port; and when the airbag bumps against a target object of protection halfway of inflation, inflation gas is exhausted out of the airbag via the communication port; and when the airbag is completely inflated, the communication port is closed with the terminal portions of the upstream side and downstream side base cloths contacted with each other.