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All About Airbags

How Airbags Work

When an accident occurs, airbags inflate faster than you can blink your eye. Airbags are key components in automotive safety systems, and, although we cannot see them perform under normal conditions with the naked eye, they soften the impact of collisions by keeping passengers from contacting the steering wheel, dashboard, front glass, and other parts of the automobile.

So, to explain what airbags actually do when an accident occurs, let’s use an example of a typical head-on collision.

*From this point forward, we will use the driver side airbag as our example and explain the way an airbag works. Figures are given as a reference.

How Airbags Work

After a vehicle collision has been detected, airbags inflate faster than you can blink your eye. Airbags are key components in automotive safety systems, and, although we can see them perform with the naked eye, they soften the impact of collisions by keeping passengers form contacting the steerling wheel, dashboard front glass, and other parts of the automobile. So, to explain what airbags actually do when an accident occurs, let´s use an example of a typical head-on collision.(*Frome this point forward, we will use the driver side airbag as our example and explain the way an airbag works. Figures are given as a reference.)

*T means the time of collision

  1. T +
    0.003

    second—Sensors detect the impact

    As the satellite sensors (collision sensors) attached to the vehicle detects the collision, a signal is sent to the ECU (Electronic Control Unit).

    Image
  2. T +
    0.015

    second—Evaluation of the impact

    The signal sent from the satellite sensors to the ECU is processed, and the ECU determines the severity of the impact based on inputted data. If the ECU determines that an airbag deployment is necessary, it sends a signal to initiate the airbag inflators (gas emitting devices).

    Image
  3. T +
    0.020

    second—The airbags go into action

    The inflators are activated through an igniter, causing a chemical reaction that emits gas, resulting in the deployment of the airbag cushion.

    Image
  4. T +
    0.040

    second—Inflation of the airbags is completed

    The force of the collision reaches the passengers, and they begin to move forward. By this time the airbags are fully inflated and they are ready to receive and restrict the movement of the passengers. The inflation of the driver side airbag takes between 20- 30 milliseconds. For the passenger side airbag, it takes between 30-40 milliseconds.

    Image
    Key Point!
    The time to inflation is measured in milliseconds. This is less than half the time it takes for us to blink an eye, which requires between 100 and 200 milliseconds.
  5. T +
    0.060

    second—Passenger motion energy is absorbed

    By this time, the airbags are fully inflated. The motion energy of the passengers are absorbed by the crushing of the vehicle, the seat belt load limiter, and the airbags.

    Image
  6. T +
    0.120

    second—Passenger motion energy is fully absorbed

    The energy of passenger movement is fully absorbed.

    Image
    Key Point!
    The proper name for airbags is “Supplemental Restraint Systems,” and as the name suggests, they play a supplementary function in protecting the passengers. Airbags can only be fully effective when they are used in combination with seat belts.

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