In June of this year, Autoliv unveiled a breakthrough to reduce fatalities and injuries caused by vehicle impacts with people. The system consisted of an ‘Active Hood’ that raises instantly when a pedestrian is hit. By lifting the hood, the pedestrian’s head contacts a deformable and flexible surface instead of a hard and rigid one. The new device also prevents a pedestrian from hitting the lower part of the windshield.
Since the June unveiling, Autoliv has further enhanced the system by introducing a pair of airbags – one at each windshield pillar – as a supplement to the Active Hood. These new Pedestrian Protection Airbags (PPA) have been shown in laboratory test to drastically reduce the risk for life-threatening head injuries.
‘As vehicle hoods tend to become shorter with every new model change, the risk of pedestrians hitting the hard structures around the windshield increases’, explained Autoliv’s research director, Professor Yngve HÃ¥land. ‘For this reason, we complemented our initial system by integrating pedestrian protection airbags at the windshield pillars.’
The Active Hood design, which is patented, consists of compressed bellows that are filled with gas within a fraction of a second. One bellow on each side of the hood raises the rear part of the hood approximately 10 cm, which is enough to prevent the head from hitting the car structure and other rigid parts. A sensor in the car bumper triggers inflation of the bellows.
The Active Hood system has proven to be very efficient in laboratory tests. The critical measurement – which in these cases is Head Injury Criterion (HIC) – have been reduced by as much as 90 percent, and HIC-values below 800 have been recorded in tests conducted according to EU standards.
These results compare favourably with the 1,000 HIC, which is the most demanding level in the planned tests.