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How does an airbag work?

Updated on August 19, 2013

What is an airbag

An airbag is a safety mechanism that is fit in every car to safeguard the passengers during crash. Accidents that happen today are fatal without airbags. An airbag is made up of flexible fabric cushion or envelope that inflates very quickly during collision. Airbags are fit in a variety of places according to customer's convenience. In other words airbags can be called as soft pillows to land on when vehicles crash.

The first airbag was designed by Allen Breed in 1968. Ford was the first company to introduce airbags in cars by 1971. Later General Motors introduced them into Chevrolet cars. Cadillac also brought airbags into their system soon. All the introductions made airbag an optional attachment until 1988 when Chrysler made it as a standard equipment.

Parts of an airbag

"Every body continues to be in a state of uniform motion unless compelled by an external force to change its state of motion" - Newton's Law

When a car crashes, the restraint system is supposed to stop the occupant from moving further. This requires enormous force to hold the person in place in a very short span of time. If the driver moves further, he/she results hitting the steering wheel causing major injury. The main aim of airbag is to prevent this quickly.

The main parts of any airbags are very simple as follows :

  1. Airbags itself form an integral part of the system. It is made up of nylon fabric and it is folded and kept inside the dashboard of the car.
  2. Inflator is an important component produces gas to inflate the airbags. This part contains a mixture of sodium azide, potassium nitrate and silicon-dioxide. During crash, these react to produce hot nitrogen gas which deploys airbags from its shell.
  3. Sensor is used to trigger the reaction in the inflator. They obtain their data from the vehicle accelerometers.

How does an Airbag work

Airbag control unit contains a number if sensors like pressure sensor, impact sensor, accelerometers which are continuously monitored.These detect the crash at any instant. When the car detects a crash, then these sensors send signal to inflators in about 15 milliseconds depending upon the severity of crash.

When airbag has to be deflated, sodium azide and potassium nitrate react in a series of steps to produce nitrogen gas. This nitrogen gas inflates airbags at 250 mph. This action is timed to occur exactly in 25 milliseconds after the crash. The inflation continues for another 20 milliseconds. This is exactly timed with the occupant's landing on airbag. This airbag remains inflated for about 60 milliseconds and then it begins to deflate after the passenger is pushed away. The deflation takes place for another 30 milliseconds.

Importance of Airbags

Types of Airbag

Airbags are classified based upon their end usage. They can be fit at all places in a car to protect the occupant from various sides and frontal impacts. They are classified as follows:

  • Driver Airbags: Safeguards the driver from frontal impact. It mainly protects the driver's face from hitting the rigid steering wheel during collision. These are placed inside the steering wheel.
  • Passenger Airbags: Protects passengers from colliding the front dashboard. It is present inside the dashboard
  • Knee Airbags: Protects the knee during impact. This airbag is also present in the passenger dashboard section.
  • Side Airbags: Safeguards passenger from side collision. This airbag is present along the side railings of the car.
  • Curtain Airbags: Present on the top of the car. It protects occupants during a car roll over and prevents brain injury at a larger scale.
  • Pedestrian Airbags: These airbags are protects the pedestrians when they are hit by cars.
  • Center Airbags: Avoids side collision of passengers and are present mostly in the rear seats.

Aibags without Seatbelt can be fatal

Airbags are effective only when seat belts are used. Seat belts restrict the movement of the occupant during crash. It holds him the person from moving further. When seat belts are not used, inflation of airbags can push the person away leading to further injuries.

During collision, seat belts pull the occupant towards the seat, thus perfect cushioning is provided by airbags. On the other hand, if seat belt is not present, the passenger tends to move further into the airbag without any pulling force. The image depicts this phenomena.

© 2013 Sadhave


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      kumar bunny yadav 2 years ago

      good information ......tnq