Patent ID: 7543849

Claim:
An inflatable airbag defining an inflatable chamber for fluid connection to an inflator, the airbag comprising: an elastic inner membrane provided in a peripheral wall of the airbag; a vent-hole formed through the elastic inner membrane; and an outer membrane provided on the outside of the airbag so as to extend across at least part of the inner membrane and the vent-hole, the outer membrane defining a pucker over the part of the inner membrane, the pucker being open so as to define an outlet flow path from the vent-hole when the part of the inner membrane is spaced from the pucker; the inner membrane being configured to stretch and seal against the pucker, around the vent-hole, when internal pressure within the inflatable chamber exceeds a predetermined value, wherein the pucker takes the form of a loose fold across the outer membrane and is open at both of its ends.