It has been just about a year since Ford announced that the company would make available an inflatable rear seat belt that would incorporate airbag technology in a seat-belt application to protect rear passengers.
USA Today reported that the restraints that double as air-bags would be an option costing about $395 on the 2011 Ford Explorer SUV. The belts will be available to the two outboard passenger seats in the second row of the three-row edition of the vehicle. Ford says that they came up with the design in-house as opposed to a component supplier being responsible for the innovation.
The inflation of the bag, which when deployed looks like a giant sausage, was a hurdle Ford had to overcome. The proximity to the passenger’s chest eliminated the use of the traditional heated gas that is used to protect front passengers, so they have designed a cold gas system that utilizes a canister housed under the seat. In crash conditions the cold gas is introduced to the bag through a special seat belt buckle and into the hollow belt which peels away as the internal bag inflates.
The science of rear seat protection is discussed in this video which demonstrates the deployment of the inflatable seat belts.