Vehicles are at their most vulnerable in a side impact as there is no extra amount of sheetmetal to serve as a “buffer” in a collision. ZF TRW, ZF's branch for automotive systems, modules and components, are currently developing airbags for a vehicle's exterior to serve as an extra cushion in a side impact.
Airbags for vehicle exteriors are a relatively new technology. The first car to be equipped with an exterior airbag is the Volvo V40. The exterior airbag in the Volvo was designed to deploy in an event of a pedestrian collision with the purpose of softening the impact between the pedestrian and the car's hardest points, namely the hood creases and the base of the windshield. This time around, ZF TRW is experimenting whether or not vehicle to exterior airbags will minimize damage in vehicle to vehicle impacts.
Plans to make exterior airbags began as far back as three years ago. Last month, ZF TRW demonstrated their first prototype for the new airbag. For this prototype, the airbag is stored in the car's frame rails beneath the doors and is set to deploy just before impact. The device is “around twice the size of a side curtain airbag” when inflated and needs 200 liters of air to fill. According to Steve Peterson, ZF TRW's director of global systems engineering for occupant safety, the airbags reduce collision forces by 30 percent.
Apart from the exterior airbags, ZF TRW is also developing a ceiling mounted central airbag that prevents limbs and debris flinging around in a crash, as well as front seat mounted airbags for rear passengers.