Tuesday, May 1st 2012
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Pedestrian protection airbag

Technology update May 2012

May 2012

At this year's Geneva Auto Show, Volvo Car Corporation introduced the new Volvo V40. The vehicle is equipped with the world's first pedestrian protection airbag. The airbag inflates on the exterior of the vehicle, covering approximately one third of the windscreen area and the lower part of the A-pillar. It's the first series application of an airbag on the exterior of a vehicle. Read more about the pedestrian airbag in our technology update!

 

The primary task of the new pedestrian airbag is to reduce the degree of injury to pedestrians in the event of a collision. The pedestrian airbag system is a supplement to the vehicle's existing mechanical structure that is designed to absorb energy in the event of a collision with a pedestrian and to stop pedestrians from impacting with hard-points at the front of the vehicle. This is an addition to other active safety features such as Volvo's pedestrian detection with full auto brake, which can detect if a pedestrian steps out into the road in front of the car. If the driver does not respond in time, the car can warn and automatically activate the brakes.

The pedestrian airbag system in the new Volvo V40 consists of a control unit called a pedestrian protection module (PPM, 1), the pedestrian protection airbag (2), two hinge release actuators (3) and seven pedestrian collision sensors (4).

PEDESTRIAN COLLISION SENSORS AND PEDESTRIAN PROTECTION MODULE (PPM)
There are seven pedestrian collision sensors (acceleration sensors) installed in the front bumper. The pedestrian protection collision sensors are continuously sending data to the pedestrian protection module. In the event of a collision, the PPM uses data from the pedestrian protection collision sensors to determine whether the severity of the collision is sufficient to activate the hinge releases and pedestrian protection airbags. The system is only active at speeds between 20 to 50 km/h and cannot be deactivated by the driver.

 

PEDESTRIAN PROTECTION AIRBAG AND HINGE RELEASE ACTUATORS
The pedestrian protection airbag is a single stage airbag located under the cowl between hood and windscreen. The airbag uses stored gas inflator technology to produce the necessary gas to fill the airbag. Upon pedestrian protection airbag activation, the airbag deploys over the lower part of the windscreen and parts of both A-pillars to soften possible impact of the pedestrian's body parts.

In addition to the pedestrian protection airbag the two hinge release actuators mounted to the hinge at each side of the hood are also activated. These actuators are equipped with a single stage micro gas generator that actuates a piston which pulls out a pin to releases the hinge. The hood is then raised by the pedestrian protection airbag, increasing the distance between hard parts of the engine and the hood itself to soften the impact of the pedestrian.

 

EXTRICATION PERSPECTIVE
"The new pedestrian protection airbag is the first airbag that deploys on the vehicle's exterior. It will probably not have been deployed following a high-speed frontal collision and therefore has the same hazard potential than any other undeployed airbag. From an extrication perspective it's important to always remember the basics, when dealing with undeployed airbags" says Moditech's extrication expert Jörg Heck. "Switching the ignition to the off position and, if possible, isolating the vehicles electrical system are very important measures to keep in mind. In addition, rescuers should always maintain a safety distance from an undeployed pedestrian protection airbag, while working on the crashed vehicle with heavy equipment. Therefore it's essential to know what's inside!"

The new Volvo V40 has already been added to the Crash Recovery System online update in March. The vehicle schematic also contains interactive information on the new airbag application.