This invention relates generally to vehicle air bags and, more particularly, to vehicle air bags having internal tethers for controlling air bag deployment.
Driver-side air bags have become quite common recently. These air bags are typically stored within the hub of the vehicle steering wheel and deploy to the shape of a flattened sphere. Since the air bag deploys from such a small storage space, it is desirable to assure that the air bag deploys to its full diametral dimension, or as broadly as possible, to cushion the vehicle driver.
Many driver-side air bags are provided with internal so-called "suspension belts", or tethers, to assure full breadth of deployment. These tethers comprise strips of webbing sewn to the air bag about its gas inlet and to the crown of the air bag body opposite the inlet. These tethers are provided to restrain rearward movement of the center of the air bag, thus assuring that the sides of the air bag will deploy.
Such arrangements are disclosed in U.S. Pat. No. 4,887,842--Sato and U.S. Pat. No. 5,033,771--Miyauchi et al. The Miyauchi patent is directed to providing a tether attachment which assures that the sewn attachments cannot break so that the center of the air bag cannot deploy further rearward toward the occupant.
All air bags for vehicle occupants, whether provided for drivers or passengers, are designed for use in conjunction with conventional seat belt systems. As such, they are normally designed to deploy to engage and cushion a normally seated and belted occupant. However, it has been found that some vehicle occupants fail to utilize the seat belt systems provided. In this instance, it is possible for the deploying air bag to prematurely contact a vehicle occupant who has moved out of the normal seated and belted position.
In this instance, it is desirable that the air bag quickly be deployed as broadly as possible to provide contact by the occupant with a full-width air bag. It is also desirable to assure initial downward deployment of the air bag to assure contact with the lower torso of the occupant.