Volvo Car Corporation’s Pedestrian Airbag Technology—applied for the first time in the new V40—relies on seven sensors embedded in the front of the car which transmit signals to a control unit. When the car comes into contact with an object, the signals change. The control unit evaluates the signals and if it registers what it interprets as a human leg the pedestrian airbag is deployed.
|Pedestrian Airbag Technology, bag deployed. Click to enlarge.|
The hood hinges are each equipped with pyrotechnical release mechanisms which, when the system is activated, pull out a pin and release the rear of the hood panel. At the same time, the airbag is activated and starts filling with gas. During the inflation sequence the airbag raises the hood ten centimeters; the hood stays in the raised position.
The added gap between the hood and the hard components in the engine compartment gives space for the hood to deform, creating a dampening effect when it is hit by a pedestrian.
The purpose of the airbag is to help protect pedestrians in certain situations when they impact the bonnet [hood] and the area around the windscreen wiper recess and A-pillar, where there may be a risk of serious head injuries. The airbag has two functions. Firstly, it raises the bonnet to create distance, and secondly it cushions the impact around the hard parts of the area near the windscreen.—Thomas Broberg, Senior Technical Advisor Safety, Volvo Car Corporation
In its inflated position, the airbag covers the entire windscreen wiper recess, about one-third of the windscreen and the lower part of the A-pillars. The entire sequence from activation of the system to full inflation takes a few hundredths of a second.
In China 25% of traffic fatalities are pedestrians. In Europe the figure is 14% and in the USA 12%. Far larger numbers of pedestrians are injured. The most serious head injuries involving pedestrians and cars are caused by the hard structure under the hood panel, the windscreen’s lower edge and the A-pillars.
The system is active at speeds between 20 and 50 km/h (15.5 to 31 mph); 75% of all accidents involving pedestrians take place at up to 40 km/h (25 mph).
Two years ago, Volvo Car Corporation launched Pedestrian Detection with full auto brake. The system can avoid a collision with a pedestrian at speeds of up to 35 km/h (22 mph) if the driver does not respond in time. At higher speeds the focus is on reducing the car’s speed as much as possible before the collision.