Ford Motor Company: Anatomy of a Crash: New Safety System in Motion
6 January 1999
Ford Motor Company: Anatomy of a Crash: New Safety System in Motion DETROIT, Jan. 6 -- One icy winter afternoon in the future, a
small-statured woman's truck hits the back of another vehicle at 8 mph.
Meanwhile, across town, an averaged-size man driving a sedan slides through an
intersection at 40 mph, crashing head-on into the side of a tractor-trailer
making a turn.
Two different accidents. Two differently sized drivers. If each is
driving a Ford vehicle equipped with the Advanced Restraints System,
two distinct vehicle safety system responses will result.
"Every accident is as unique as the individuals involved," said Helen
Petrauskas, vice president - Environmental and Safety Engineering. "Bearing
that in mind, Ford has worked hard to develop a safety system that can provide
people of different sizes, facing various types of frontal crash situations a
restraints system that automatically tailors itself based on certain crash
conditions."
What would happen in these two crashes? The driver air bag in the small-
statured woman's truck likely won't deploy in an accident this minor --
especially if a sensor in her safety belt buckle indicates she is wearing a
safety belt.
However, the driver's-side air bag in the man's sedan will deploy at the
highest available inflation rate because of the high speed and severity of the
crash as well as the position of his seat away from the air bag.
Had the man been driving more slowly, the driver air bag might have
deployed at a lower inflation rate. Air-bag energy levels will be tailored to
a threshold that corresponds to estimated crash severity, safety belt use and
driver seat position.
In either case, the vehicle's front-passenger air bags would not have
deployed because the passenger-seat weight sensor would have indicated that
the seat was unoccupied. If the woman had placed her briefcase in the
passenger seat, the front passenger air bag still wouldn't deploy because a
weight sensor in the passenger seat would have told her truck's safety system
"brain" that the briefcase was too light to be a passenger in need of front
air-bag deployment.
The tailored safety system responses are accomplished by nearly a dozen
Advanced Restraints System technologies, which analyze conditions at the time
of an impact and automatically deploy the most suitable safety devices
adjusted for the given crash situation.
For instance, an electronic sensor system will estimate the severity of
the crash, providing that information to the "brain" of the system that then
triggers other system components.
Within milliseconds, the "brain" of the system will activate
pretensioners, which are special devices nestled in front-seat safety-belt
buckles or retractors that tighten front-seat safety belts and help prevent
belted occupants from sliding and bouncing around during a crash. This
further improves the effectiveness of a vehicle's most important safety
feature -- safety belts.
Meanwhile, various sensors will monitor the seat position of the driver,
the weight of the passenger and the safety belt usage of each. The sensors
communicate their findings to the control module, which activates the
appropriate level of air-bag protection for both the driver and passenger.
Ford's front dual stage inflating air bags use variable-rate gas delivery
to inflate the deploying air bags in a manner that corresponds to accident
severity. This breakthrough can be achieved with sophisticated dual-stage
inflator technology. The lower, less forceful rate provides the appropriate
protection for more common, moderate-severity impacts while higher inflation
rates are required for the most severe crash events.
If crash forces increase to severe levels, a metal bar tucked in the
center of the spool of the safety belt retractor -- called an energy
management retractor -- twists like a wrung-out washcloth. This releases
small amounts of safety-belt webbing in a controlled manner and significantly
reduces the risk of force-related injuries, especially to the chest.
"The technology involved in this system is nothing short of amazing,"
Petrauskas said. "Thanks to the world's most advanced sensing and computing
technology, Ford customers truly will benefit."
