Volvo's Pedestrian Airbag system
According to Volvo’s research, 25-percent of traffic fatalities in China are pedestrians. While the numbers are lower for Europe (14-percent) and the United States (12-percent), they’re still significant.
In a pedestrian-vehicle accident, most serious head injuries are caused by the person’s head striking either a solid structure underneath the hood panel, or by striking the lower edge of the windshield or A-pillar.
That makes the lower edge of the windshield the perfect place for a pedestrian airbag, especially if deployment can raise the rear height of the hood assembly to reduce the chance of impacting anything solid beneath the panel.
Volvo’s system uses an external airbag, mounted in the wiper recess. When a series of seven forward-looking sensors detect the presence of something the size and shape of a human leg, pyrotechnic charges release pins that anchor the rear of the hood, milliseconds before the pedestrian airbag is deployed.
The whole process takes just a few hundredths of a second, and the net result is an airbag that covers the lower portion of the windshield and A-pillars, while simultaneously raising the rear of the hood by nearly four inches.
That four-inch space is enough for the hood to cushion the impact of a collision with a human body, reducing the chance of serious injury.
The system is designed to work at speeds between 20 and 50 km/h (roughly 12.5 to 31 mph), since 75-percent of pedestrian impacts occur at speeds under 40 km/h (25 mph).
Volvo’s Pedestrian Airbag system debuts on the new V40, and joins the automaker’s already-implemented Pedestrian Detection system with full auto brake, which can prevent a collision with a pedestrian at speeds up to 35 km/h (22 mph).