Mercedes-Benz ESF 2009 safety concept car, driver seat vertical central head curtainEnlarge Photo
One problem in both side impacts and rollovers, Fehring said, is that even occupants belted tightly in their seats can have their extremities flung around.
To keep the driver's head in place, the ESF has a very stiff vertical side curtain that inflates from shoulder level upwards. It keeps the head in position, helping to "cocoon" the driver and prevent driver and passenger heads from knocking together.
mercedes benz esf 2009 experimental safety vehicle 007Enlarge Photo
INFLATABLE REAR-SEAT BELTS
Rear passengers have no frontal airbags; they're simply too hard to engineer into the front seatbacks. Seeking ways to reduce injuries to the collarbones, sternum, and thorax of rear-seat riders, the ESF engineers looked at ways to distribute the forces of their seat belts over a wider chest area.
The result was an inflatable seatbelt, or "beltbag," to spread decelerative loads across twice the surface area of a standard belt. Fehring said the team spent a great deal of time on "the haptics and optics" of the design, to ensure it wasn't unpleasant to put on or wear.
The belt bag is contained inside a strap that is just twice the thickness of regular seat-belt webbing, though Fehring noted that measuring comparative injuries from a seatbelt and a belt bag was a challenging problem for which instrumentation doesn't yet exist.
Mercedes-Benz ESF 2009 safety concept car, Inter-Seat Protection system activated in rear seatEnlarge Photo
REAR SEAT HEAD BOLSTERS
Similar to the front-seat vertical air cushion, the ESF team created an Inter-Seat Protection system to keep rear-seat passengers properly located. It's one of the few new technologies, in fact, that doesn't actually inflate.
Instead, a pair of padded bolsters at the top of the rear seat center pops up, out, and forward to prevent each outboard passenger's head from moving toward the center.
The most futuristic idea in the ESF is the "braking bag," a large standard airbag covered in rubber over a steel mesh. When a collision is imminent, the bag (located just ahead of the front axle) deploys, inflating downward and actually bouncing the car upwards.
This has several advantages: It slows the vehicle further by adding contact area beyond simply the four tire patches; it stabilizes the vehicle; and it raises the front end to compensate for "dive" to provide a better height match between two colliding vehicles.
The video below shows the braking bag in action, though Fehring stressed that "it needs a lot of work" before the company will even consider deploying it in production cars.