Patent ID: 7654561

Claim:
An inflatable cushion for use in an air bag module, comprising: a primary inflatable chamber configured for deployment from the air bag module, the primary inflatable chamber having an inlet opening for receipt of an inflation gas, the primary inflatable chamber defining a first volume when inflated with the inflation gas; and a secondary inflatable chamber secured to the primary inflation chamber, the secondary inflatable chamber defining a second volume when inflated with the inflation gas, the second volume being less than the first volume, the secondary inflatable chamber receiving the inflation gas from the primary inflation chamber through a portion of the primary inflatable chamber that is surrounded by an inlet opening of the secondary inflatable chamber, the portion of the primary inflatable chamber being configured such that the inflation gas must travel into the primary inflatable chamber and create a first predetermined pressure in the primary chamber prior to the inflation gas passing through the portion and into the secondary inflatable chamber; wherein the portion of the primary inflatable chamber includes at least one vent configured to prevent fluid flow in a first direction through the vent and into the secondary inflatable chamber until the first predetermined pressure is achieved in the primary inflatable chamber, and wherein once the first predetermined pressure is achieved, the at least one vent opens and provides fluid communication between the primary inflation chamber and the secondary inflation chamber, and wherein the at least one vent comprises a plurality of flaps configured to overlap each other and seal the at least one vent until the first predetermined pressure is achieved in the primary inflatable chamber.