Airbag is a cloth bag that quickly fills with air during an automobile collision to cushion and protect the people inside. An airbag is most effective used with lap and shoulder belts.
Loading the player...Airbags in a crash simulation
How airbags work.
An airbag system consists of one or more cloth airbags, an inflator, and devices called sensors. The sensors can detect a sudden slowdown, which would occur in a frontal collision, or the jarring force of a side impact. Sensors to detect frontal collisions are usually mounted at the front of the vehicle and in the passenger compartment. Those that detect side collisions are usually in the door and in the center pillar at the side of the vehicle. The sensors run on energy from the vehicle’s battery or from a computerized control unit, a device that also monitors the system for malfunctions.
Airbags are designed to inflate in frontal or front-angle impacts in which the automobile strikes an immovable object at more than about 10 miles (16 kilometers) per hour or another car at about twice that speed. A side-impact airbag can be triggered by less impact.
After an impact, some airbag sensors send an electric current directly to an igniter system. Other sensors may send the current to a computerized control unit, which evaluates the situation before sending the current on to the igniter system. The electric current heats a filament (wire), which ignites a capsule. The capsule, in turn, ignites gas-generating pellets.
In most systems, the pellets are made of sodium azide, which produces nitrogen gas when it burns. The gas expands quickly and inflates the airbag, causing it to break through a plastic cover in the steering wheel, the dashboard, or a door panel. The whole process takes about 0.1 second from the moment a frontal impact is detected, and even less time in the event of a side impact. The airbag starts to deflate immediately, venting the harmless gas through holes in the back of the bag or through the fabric itself.
Safety concerns.
Safety experts have raised concerns that airbags can injure children, pregnant women, and adults of below-average height by hitting them on the head or neck. Automobile manufacturers are developing systems that can adjust the position and inflation speed of an airbag based on the position and size of the person in the seat. The United States National Highway Traffic Safety Administration recommends placing all children 12 years old and younger in the back seat.
