The never-ending search for improved occupant protection keeps large teams of engineers gainfully employed. At Ford, the Passive Safety Research team has come up with a breakthrough technology that is likely to spread throughout the industry - the inflatable seat belt. The concept is simple - expand the size of the contact patch to spread the loads created during a crash over a larger area.
Ford's inflatable belts recently won AJAC's Automotive Technology of the Year award, besting 10 other entries in doing so. Jurors judged the inflatable belt to be a significant benefit to consumers, one that will become commonplace throughout the industry.
Airbags have proven a wonderful solution to reducing injury. In the front seat and for side impact protection they can be made large enough to spread and absorb forces, based on sensor information about the size and location of the occupants.
While it would appear airbags could be used in rear seats, mounted in the back of the front seats, there are problems with that, chief among them the changing location of the front seats relative to the rear as they are moved forward and backward, the fact the two front seats could be at different distances and that the rear seats frequently carry small children and car seats that could be harmed by the forces of a bag necessary to protect a large adult.
So Ford engineers, under the technical leadership of Srini Sundararajan, went to work. Putting his doctorate in biomedical engineering to good use, he has also been responsible for the development of deployable door trim systems for improved side impact protection, development of the industry's first comprehensive automatic collision notification system and innovative biomechanics research on human cervical spine movement during rear-end collisions.
The 21-year Ford veteran and his team have been working on the inflatable belt project for 10 years. "Combining the functionality of a safety belt and some of the benefits of an airbag into one occupant protection system was easier said than done," he said during a presentation to the Automobile Journalists Association of Canada technical jury.
He said some of the challenges included inflation through a special buckle and a retraction system that would accommodate the thicker belt. Testing included a number of real world situations - including having dogs chew the belts and pouring various liquids and gooey substances into the buckle mechanism.
The same sensors used to provide information to other systems in a crash trigger the release of compressed gas from a cylinder attached to the buckle mechanism and located beneath the seat. This air fills a tubular bag contained within the chest portion of the belt within 40 milliseconds of impact. The bag breaks through the fabric of the belt, expanding across the upper body of the occupant.
The inflatable belt is especially useful in protecting young occupants with bodies that have not yet grown to full strength and are thus more susceptible to the huge forces of a collision. These same youngsters are also frequently asleep and with their head lying on the side, out of position for maximum protection from the conventional belt.
The inflatable belt acts just like a conventional belt system in a crash - except it spreads the forces over five times more area - reducing pressure on the chest, and controlling head and neck motion. Ford's research showed that 90 per cent of occupants exposed to the new belts found them more comfortable than conventional belts because of the padded feeling provided by the enclosed bag and the rolled edges of the belt.
The inflatable belt, which makes its debut on the Canadian-built 2011 Ford Explorer, will eventually be offered on all Ford vehicles globally.