Autoliv Shows New Rollover Protection System

STOCKHOLM, Sweden, June 8, 2005; At the Enhanced Safety of Vehicles (ESV) international conference held in Washington, D.C., Autoliv Inc. -- the worldwide leader in automotive safety -- showed a new seat belt and an airbag system for rollover protection. According to the tests, the system could eliminate virtually all serious head and neck injuries in rollover crashes, as long as the roof of the vehicle can withstand the ground impact without extensive intrusion.

Currently, about 10,000 people are killed annually in rollover crashes in the United States alone. In the future, many lives will be saved thanks to electronic stability control (ESC) systems and side curtain airbags that are being introduced on an increasing number of vehicles. In vehicles equipped with rollover sensors, the seat belt pretensioners could also be activated to tighten the seat belt, thereby increasing the distance between the occupant's head and the roof of the vehicle. However, the curtain airbag is designed to protect only on one side of the occupant, the so-called near-side. When an occupant moves toward the other side of the vehicle (the far-side) during the rollover crash, the upper body could slip out of the shoulder belt, creating a greater risk of injury to himself and others. As a result, 40% of the fatalities in rollovers involve far-side occupants.

Autoliv, the inventor of the curtain airbag for near-side protection, has now tested a system that addresses this problem. ``We started by simply turning a regular seat belt around and attaching the shoulder portion of the seat belt to the upper inner corner of the seat back rest instead of to the door pillar,'' explained Associate Professor Ola Bostrom, who presented a paper with the test results at the ESV conference. ``Inboard belts have been tested before. However there is a risk of injury from this type of belt to the occupant's neck and throat, at least to far-side occupants in side impacts. We think we have now solved that problem,'' said Bostrom.

Autoliv has put a small airbag at the inboard side of the back rest side (i.e., on the right side of the driver seat on a left-hand driven vehicle). This Side-Support Airbag (SSA) prevents the occupant from severe loads to the neck and the throat should the occupant slide towards the shoulder portion of an inboard belt. To reduce slack the seat belt is also tightened up to 15 centimeters (6 inches) using a pyrotechnic seat belt pretensioner. ``Our system is simple, but the tests results are very promising,'' declared Professor Bostrom. In every test conducted by Autoliv the new system succeeded in preventing the head from reaching the roof of the vehicle, while the head of the test dummies using a traditional seat belt system hit the roof with great violence.

New Specially-Designed Rollover Test Rig In order to ensure valid comparability testing, Autoliv has developed a special sled test rig. With it, the company's researchers can simulate a typical rollover when the vehicle rotates half a turn and then lands on the roof. Only the body of a car or an SUV is needed for the tests, which makes testing less expensive than traditional full-car testing. The test rig simulates all three phases in a typical rollover: 1) tripping, 2) air born and 3) ground impact. In this way it has become possible to simulate the complex motions of a human body in a typical rollover without using real vehicles.

New Specially-Designed Test Dummy

It has also been necessary to make changes to the test dummies, because their spines are stiff and rigid. In humans, however, the spine is curved and therefore the distance between the head and the hip often increases a little when the occupant is turned upside down in a rollover. Consequently, the spines of the test dummies has been modified to provide the correct elongation characteristics.