Ten Years of Side Airbags at Volkswagen
Airbags save lives. Exactly ten years ago, Volkswagen expanded the safety package then consisting of driver and passenger airbags to include side airbags. Integrated into the backrests of the front seats, these new airbags first provided protection from dangerous side impacts in the Passat. Since then, Volkswagen has built more than 12 million cars with side airbags, thus contributing enormously to the triumph of this safety technology.
- Side safety: the first “sidebags” debuted in the Passat in 1996
- Fast safety: the side airbag unfolds completely in 20 milliseconds
A side impact, which occurs in 25 – 30% of accidents in Germany, presents an extremely difficult situation for automotive engineers. In contrast to the frontal impact, the vehicle body and restraint systems must process the force of a side impact via a short deformation path — and in a very short time. And that is only possible with innovative technologies. As a globally operating company, Volkswagen based its research on the toughest criteria.
Intelligent sensor system for optimum protection
In order to provide optimum passenger protection, Volkswagen employs a state-of-the-art, multiply redundant sensor system. In the Golf, for example, sensors that react to changes in air pressure are located centrally in the front door boxes. There are also acceleration sensors in the front fenders and the rear doors (the latter in models with rear side airbags and belt tighteners). Another acceleration sensor is located on the central tunnel below the cockpit; it checks the signals from the external sensors and is coupled to the airbag controller.
Complex process in milliseconds
The controller decides whether the side airbag needs to be activated. If they do, a complex procedure starts with unparalleled speed. The ignition is triggered in just six milliseconds: a targeted jolt of current sent by the controller begins melting a fuse in the gas generator. The resulting heat activates a detonator. The airbag itself, about the size of two pieces of cake when folded together, is located in the backrest and thus always in the optimum position for the passenger.
The chemical reaction activated by the ignition of the detonator generates a gas composed primarily of nitrogen, water vapour and carbon dioxide. The gas exits the generator at supersonic speed and fills the 12-litre side airbag, whose outer skin is made of special, highly tear-resistant nylon. The airbag shoots through the rip-seam in the upholstery at over 100 km/h and forms a protective pillow in front of the door panelling. The Volkswagen side airbags cover the passenger’s entire upper body from pelvis region to head.
Faster than the blink of an eye
All of this happens unbelievably fast. A human blink lasts 100 milliseconds; in a side impact at 50 km/h, everything that counts happens much faster. The side airbag is completely unfolded just twenty milliseconds after the impact starts. And the passenger plunges into the air pillow in just another 20 milliseconds. The passenger’s weight forces the gas out through an opening in the fabric in less than a second, giving the passenger a relatively soft landing. The belt tightener, which was also activated upon impact, stabilises the upper body.
The side airbags have undergone constant improvement in the past ten years. In the Passat, for example, the forces that act on the passengers’ abdominal region are now 25% lower than in the previous Passat generation — and only a quarter of the maximum allowed in Europe. Safe and sound.