Safety is in the Bag

Dalphimetal, a Spanish subsidiary of TRW Automotive (www.trw.com), has pushed airbag technology forward with its Bag In Roof (BIR), X-Tether, and Dual-Chamber Side Airbag (DCSA) systems.

Dalphimetal, a Spanish subsidiary of TRW Automotive (www.trw.com), has pushed airbag technology forward with its Bag In Roof (BIR), X-Tether, and Dual-Chamber Side Airbag (DCSA) systems. The first conceals the front passenger airbag in the space behind the windshield header, where it deploys along the windshield and then down. The giant kidney bean-shaped bag eliminates the need to package a relatively large passenger airbag in the instrument panel, and can reduce the cost of that piece by eliminating the need for an engineered door that opens with the airbag deployment. It also increases the design possibilities available for the windshield angle and instrument panel depth and shape.

The X-Tether is a new concept for side curtain airbags that combines a one-piece woven and laminated bag with a pair of internal tethers that maintain a constant cross section. Current side curtain designs either use no tethers (oval cross section), or one tether at the bag’s centerline (elongated oval). Areas where coverage is less than optimal, called “thin spots” by airbag engineers, are possible with these designs as their lack of an internal support system allows their shape to change when contacted. The X-Tether design, however, places an upper and lower X-shaped tether in the bag, which causes it to inflate in a “figure 8” cross section. This creates a pair of optimized chambers, and eliminates thin spots. Unlike other designs, the tethers are woven at the same time as the airbag to eliminate potential leakage or tear paths.

Dalphimetal’s seat-mounted Dual Chamber Side Airbag is designed to optimize the effect on the pelvis and thorax independently by splitting the bag volume between these areas. In the latest design, vent chambers react to different size and weight passengers. For example, a smaller occupant would not block the upper vent, ensuring they would get a softer response from the airbag, while a larger and heavier person’s shoulder would block this valve to ensure the bag remained stiffer. The engineers also showed a compact head protection module for convertibles that sits atop the seat, and a seat pan airbag that inflates to raise the leading edge of the lower seat cushion to prevent occupants from sliding under their seatbelts.—CAS