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How
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Air Bags
How an Air Bag Safety System Works
(Note: if an air bag warning light is illuminated while driving
the air bag safety system has been disabled and will not activate in the event of
an accident.)
Automotive air bags are made of a stretchable membrane which inflates during a collision
to provide cushioning to the head and torso to prevent injury. The technical term
for the air bag safety system is supplemental inflatable restraint or (SIR), cushion
restraint system, or supplementary restraint system (SRS). John W. Hetrick, US Navy
retired, invented the air bag system in 1951. Air bag technology currently used
in cars is derived from a system used in aircraft in the 1940s. The original air
bags were bladders, filled with heated or compressed air. That system was quite
large in comparison with modern air bag technology, but works on the same principles.
Drivers Side Air Bag
Air bags were first commercially available in the 1970s. At that time drivers
were not required to wear seatbelts and air bags were considered a seatbelt replacement.
In 1971 Ford introduced an experimental air bag system and became the first company
to do so. General Motors followed in 1973 introducing a new system, which had two-stage
deployment, in their Chevrolet cars. At that time these systems were known as air
cushion restraint system. One significant difference between the early airbags and
those used today is that the passenger side airbag was placed at the bottom of the
dashboard, protecting the knees, instead of above the glove compartment.
The initial air bag system was enhanced and replaced with the supplemental restraint
system or SRS. It was introduced in the S-Class Mercedes-Benz in 1980. The seatbelts
were also made to tighten at the time of an accident to maximize the benefit of
the airbag. The 1987 Porsche was the first to introduce the passenger side airbag.
The center of the steering wheel contains the airbag inflator module, which contains
the nylon airbag and inflator unit. In case of an accident, an electrical signal
is sent to the system that releases gas through a hole located behind the airbag
inflator, which immediately fills the bag. The electric signal is passed through
the coil assembly located on the steering column beneath the inflator module. This
electric signal is converted to heat, which burns the copper oxide, which converts
to nitrogen gas and fills the air bag. In the passenger side, the area above the
glove compartment holds the air bag and SRS is displayed on the compartment, which
means supplemental restraint system.
Air Bag in Steering Column
The rest of the airbag, airbag inflator module and electric coil assembly on
the passenger side are the same as that in the steering wheel unit. The airbag is
contained within a trim cover, which has a molded seam through which the airbag
inflates open after the seam splits. The driver's side and passenger side airbags
cannot prevent rollover crash injuries, side impact and rear impact. Later, side
impact air bags or the side curtain airbags were introduced to counter this problem.
These air bags are located near the exterior side of the seat backs or interior
side molding to protect the body. Some side air bags can be located in the roof,
back seat outboard edge or the door. The door pillar near the bottom holds the impact
sensors, which sends out electric signals to inflate the side impact air bag. (NOTE:
If your air bag light is on or flashing the air bag safety system will not work
in the event of an accident).
Air bag technology has advanced greatly since its inception. Airbag triggering
systems have become more advanced and sophisticated, helping to prevent injury and
death. Conditions like proximity and position of the passenger, severity of crash,
and belt usage are being considered prior to SRS action. To reduce the force and
impact of airbags, multi-stage inflators have been developed to help control the
force of deployment based on whether the crash was severe or moderate. According
to a research, air bags when accompanied with seat belts, reduces the number of
deaths due to automobile accidents by about eight percent.
Air Bag Deployment
Air Bag System Information
Even in the case of power failure or cut-off, the diagnostic and sending module
is capable of providing electricity to all the airbag systems. This module is checked
every time the automobile is turned on. In case of failure, an ABS warning light
will flash or stay on constantly asking for immediate attention. Special care must
be taken when disconnecting the anti-theft system and the battery so as not to effect
the functioning of the airbag module. The car must be turned off completely with
the wheel in a straight position. The battery must be carefully disconnected from
negative terminal and then followed by the positive terminal and a manufacturer
specific amount of time must pass to allow for capacitor discharge. When working
with the airbag module, do not face it towards the body or any surface in case of
accidental inflation to avoid injury.
Airbags inflate when the car hits an object at the speed of 8-14 MPH. They automatically
deflate at a temperature of 300-400 degree Fahrenheit, in case of fire. The efficiency
of the system increases when it is used along with a seatbelt because the body is
properly positioned. It is always recommended to wear the seat belt when the vehicle
is in motion. The passenger in the front seat should be away from the air bag about
10 cm at all times to avoid any adverse effects to the passenger in the event of
an accident.
How
Does it Work /
Air Bags
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