A Safer Airbag

Studies have shown at least a third of all airbag-related injuries are facial in nature.

The U.S. National Highway Traffic Safety Admin. says airbags typically deploy at speeds of about 100 mph (160 km/h) and can cause scratches and scrapes, and, in rare cases, eye injuries.

With these statistics in mind, Toyota Motor Corp.'s Lexus luxury division designed what it calls the world's first twin-chamber airbag, which it hopes will mitigate facial injuries. It is first being featured on the new '06 Lexus IS sport sedan but most likely will roll out to other vehicles in the auto maker's lineup.

Many auto makers and suppliers have engineered technology to lessen the severity of airbag deployment. General Motors Corp. has so-called dual-depth front passenger airbags that deploy in two different sizes and at two different pressures.

However, the Lexus approach with its twin-chamber bag is relatively simple and cost-effective.

“The primary advantage is just preventing impact to the face and distributing it more to the shoulder area, which is stronger and has less opportunity for damage,” says Bob Allen, dealer education manager for Lexus College, of the twin-chamber design.

Lexus College is part of the University of Toyota, a division of Toyota Motor Sales U.S.A. Inc., which is responsible for educating TMS employees and dealers.

Besides the human cost, “facial injuries are quite expensive for insurance companies to take care of,” Allen says.

The technology is basic. Toyota and its airbag supplier, Takata Corp., jointly developed the new twin-chamber airbag by sewing together two smaller kidney-shaped bags. There is a seam that joins the two bags, running vertically down the center.

The seam creates a depression where a traditional airbag would be flush, providing space for a person's nose and other delicate facial features in the event of a deployment. The airbag's full force is felt most on the occupant's shoulders and upper torso, where the two chambers make the most contact, and where the threat of injury is lessened.

The bag is employed only in front of the IS' passenger-seating position due to space constraints in the steering wheel and the need to keep the twin-chamber bag stationary.

“The steering wheel turns, so you don't have a consistent deployment of it (the airbag) as you would with the passenger side,” explains Allen of the need for a fixed deployment.

Allen says the twin-chamber airbag deploys in the same fashion as Toyota's other multi-stage airbags, is made of the same nylon fabric and costs the same as a traditional single-chamber airbag to manufacture and install. “It's basically the same module that's deploying it. The only difference is the design of the bag,” Allen says.

The replacement cost is the same for the twin-chamber bag, as well.

Adults of various shapes and sizes should be protected equally, but Allen cautions the new IS does not have an occupant detection system to sense whether a small child is seated in the front passenger seat.

As with all auto makers, Lexus recommends the front passenger seat be reserved for adults, with small children seated in the second row.

Real-world performance data on the twin-chamber design has yet to be collected, as the new IS models, the 250 and 350, go on sale in mid-October in the U.S.

But Allen says internal analysis with crash test dummies has shown the new twin-chamber design “will prevent injury to soft tissue in the facial area by distributing it more in the torso and shoulders.”