What is a depowered airbag

How does an airbag work?

How does an airbag work?

Airbags have been protecting car occupants who have been involved in an accident since the late 1970s. The life-saving air cushion was invented much earlier: the engineer Walter Linderer applied for a patent in 1951.

Whether or not the airbag is deployed naturally depends on the severity of the accident. But how does the car even know what a blatant accident was?

Who gives the command to the airbag?

This is directly related to the airbag Control unit of the carriage. This is, so to speak, the boss of the airbag: the control unit decides whether the protection is used or not.

Various sensors on the vehicle help him to do this, delivering and evaluating measured values. In short: the data informs the control unit whether your accident was serious enough at all.

Because if the control unit comes to the conclusion that you only touched another car lightly, it will not trigger any airbags. On the other hand, if the crash was bigger, it will take the protective measure.

The steering wheel airbag and its components

Now imagine that you are behind the wheel of a car. Then there is the steering wheel airbag in front of you, in the steering wheel. The consists of the following components: the steering wheel cover (this is the part that is visible to you), an air bag, an air bag holder and a gas generator.

For us, the airbag and the generator are exciting at this point. The airbag is the pillow that ultimately protects you from bad injuries. But it's still crumpled in your steering wheel. So what has to happen for it to inflate and unfold?

Two cases: pill or gas?

First of all: At this point there are two cases that have to be distinguished. In some airbags, the air cushion is filled with the help of chemical substances that are present as solids. Others contain the chemical that inflates the airbag air cushion compressed gas in front.

Let's start with the solid.

Case 1: the tablet first

If the control unit is of the opinion that you need an airbag, it will come Gas generator in the game. It contains the propellant charge. This propellant charge is in this case as Solid in the form of many tablets. They are classically made of sodium azide.

The Gas generator a so-called Squib. And now the starting shot follows: If you have had an accident, this detonator is ignited. This is done by using electricity to heat a thin wire.

This leads to the Propellant charge - the sodium azide - is burned off. This creates gas. This then reacts with an oxidizer, for example copper or iron oxide. Now nitrogen is produced. And this nitrogen fills the airbag. It is now available as a pillow to protect you.

Incidentally, this reaction is not without: pressure and heat are generated. More precisely: up to 700 degrees. So that you don't get injured in your car, the gas is cooled down before it escapes. All of this happens within milliseconds.

The problem: the sodium azide is poisonous and therefore difficult to dispose of. This is why alkali chlorates have also been used since the late 1990s. Or you can rely on other gas generators.

Case 2: step on the gas

For example on Hybrid inflatorsthat are used more and more frequently. They work a little differently: they don't have the chemical substance as a tablet, but as a compressed gas. It refers to Nitrogen or an argon-helium mixture.

The gas is stored in a pressure bottle. This pressure bottle is powered by a membrane locked. If the starting shot is now given, a propellant is also burned off. Compared to the first case, the amount is small.

By burning the Propellant the membrane is opened: The bottle is no longer "sealed" - the gas can escape and fill the airbag.

The advantage: Due to the small amount of propellant, the hybrid gas generators are more environmentally friendly than conventional solid fuel generators.

By the way, there is more from the smart-ass knowledge category in our articles on sports drinks, the periodic table or indigo blue.