An airbag includes two base cloths sewn together at their outer peripheries by a seam extending from a central portion to the outer periphery of the base cloths into a vortical shape. When gas is supplied from an inflator to a center aperture of one of the base cloth to inflate the airbag, load generated by gas pressure breaks the seam sequentially from the central portion to the outer periphery, preventing sudden deployment of the airbag in fore and aft directions at the initial stage of deployment, thereby enabling not only soft restraining of passengers but also sufficient restraining by deploying the airbag into a final shape that is flat in fore and aft directions upon completion of breaking of the seam. The seam comprises a plurality of bonding portions such that the inflation breaks each of the bonding portions sequentially.
CROSS-REFERENCES TO RELATED APPLICATIONS
The present application is a divisional of prior U.S. patent application Ser. No. 10/932,875, filed 2 Sep. 2004, which claims priority under 35 USC 119 based on Japanese patent application Nos. 2003-317761, filed 10 Sep. 2003, and 2003-411899, filed on 10 Dec. 2003, and 2003-412200, filed on 10 Dec. 2003 and 2003-417862, filed on 16 Dec. 2003 and 2004-188825, filed on 25 Jun. 2004 and 2004-188826, filed on 25 Jun. 2004. The subject matter of each of these priority documents is incorporated by reference herein.
Priority Data
Sep 10, 2003 [JP] 2003-317761 Dec 10, 2003 [JP] 2003-411899 Dec 10, 2003 [JP] 2003-412200 Dec 16, 2003 [JP] 2003-417862 Jun 25, 2004 [JP] 2004-188825 Jun 25, 2004 [JP] 2004-188826
