Bumper airbag with multiple chambers

An inflatable multi-chambered bumper airbag system for a motor vehicle having a bumper comprising;

• a housing mounted inboard of the bumper and having a door flush with the outer surface of the bumper;
• a folded, non-inflated bumper airbag mounted in the housing behind the door, the airbag having a plurality of concentric chambers circumferentially disposed around a main chamber with each of the chambers separated from adjacent chambers by seams of frangible thread;
• at least one sensor mounted on the vehicle for sensing an imminent collision with an object and generating a signal therefor;
• a control unit having a microprocessor having an algorithm stored therein for processing the signal from the sensor and generating a firing signal before the collision occurs;
• and
• an inflator responsive to the firing signal and operatively connected to the main chamber for supplying inflation fluid to the main chamber, whereby the main chamber inflates, burst through the door and forms an inflated cushion barrier extending at least partway across the vehicle.

A method for fabricating a multi-chambered bumper airbag comprising the steps of:

• a) providing a first fabric the member having a first perimeter;
• b) providing a second fabric member having a second perimeter;
• c) positioning the first and second fabric members so that first and second perimeters align;
• d) sewing a first frangible seam inboard of the perimeter for binding the first and second fabric members together to define a main chamber circumscribed by the first frangible seam;
• e) sewing a second frangible seam radially outward from the first frangible seam for binding the first and second fabric members an to define a second chamber concentric with the main chamber;
• f) sewing a non-frangible seam adjacent the first and second perimeter for joining the first and second fabric members and forming a third chamber concentric with the second chamber;
• and
• g) mounting a gas inlet valve through the first fabric member.