How do Airbags Work in Vehicles?

After the seat belt, the airbag is one of the passive safety elements that has saved the most lives. Patented by Mercedes in 1971 and launched on the market in 1981 as optional equipment, all manufacturers have incorporated it into their vehicles to help protect their occupants in the event of an accident effectively.

Also known as an airbag, air cushion, or SRS, for its acronym in English “Supplemental Restraint System,” it is a passive safety system installed in the vast majority of cars. It serves as a complementary safety mechanism to the seat belt system in motor vehicles.

Its main task is to deploy a flexible structure that, by using the compressed gas it contains, reduces the severity of the impact on one or more parts of the driver’s and occupants’ bodies at the time of a traffic accident.

The airbag system of a vehicle consists of:

  • Impact detectors, typically located inside the car, that activate in the event of a collision using sensors.
  • Inflation devices, which, through a chemical reaction, produce a considerable amount of gas almost instantaneously.
  • Nylon bags, usually inflated with nitrogen generated by the chemical reaction.

In the event of an impact or collision, the airbag quickly activates to mitigate the impact on the vehicle’s occupants, who generally collide with the steering wheel, dashboard, or passenger compartment, as well as the windshield and side windows.

How does the airbag work? The car is equipped with kinematic sensors that detect a collision and send an electrical signal to a detonator located next to the gas generator. This generator, situated adjacent to the airbag, contains a solid chemical compound. The detonator initiates a reaction that produces enough gas to inflate the airbag rapidly.

At the moment of impact, as the head and torso of the driver and occupants move forward, the airbag intervenes to prevent the collision. After serving its purpose, the gas escapes through holes in the upper part of the bag, allowing the driver and occupants to regain their vision as quickly as possible.

The inflation process during an impact takes about 3 milliseconds, with the airbag deploying at a speed of approximately 300 km/h. The rapid deployment of the airbag can cause injuries if the driver and occupants are not using the other safety systems, especially the seat belt.

Airbag Functionalities Include:

  • Absorbing part of the body’s kinetic energy to decelerate the sudden movement of the driver and occupants.
  • Preventing impacts against the car’s interior elements. Without the seat belt and if the airbag does not deploy, the occupants could be propelled through the front or sides of the car, colliding with various external elements like asphalt, other vehicles, etc.
  • Reducing the risk of injuries from windshield glass fragments.
  • Minimizing head movement, which in severe impacts can lead to fatal or cervical injuries.

Where are the Airbags Located :

Front: Located in the steering wheel for the driver and in the dashboard for the passenger, these airbags protect the head and thorax in the event of a frontal impact.

Sides: Positioned at the sides of the seats or inside the doors, they generally protect the thorax.

Roof: These are installed along the sides of the car’s roof, above the windows, primarily to protect the head.

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