How does an airbag work?

The vehicle's passive safety system includes, among other things: an airbag. Its task is to soften the head and other parts of the body of people in the car during a collision. From this text, you will learn where these mechanisms are located in the car, what controls the airbags and how to deal with their failure. Join us and expand your automotive knowledge!

What is an airbag in a car?

As we mentioned at the beginning, the airbag is one of those parts that are designed to protect the health and life of the people in the car during an accident. Previously, it was not installed on all cars. Today it is a mandatory mechanism in cars and provides an additional layer of security.

It consists of 3 main structural elements. It:

• activation command;
• solid fuel igniter;
• gas cushion.

How do car airbags work?

Modern airbag safety systems are extensive in terms of pyrotechnics and electromechanics. Based on the crash sensor signals, the airbag controller receives and interprets the sudden change in vehicle speed signal. It decides if the deceleration is due to a collision with an obstacle and activates the gas generating solid fuel tank. The airbag corresponding to the impact zone is deployed and inflates with a harmless gas, most often nitrogen. The gas is released when the driver or passenger leans on the restraint.

Airbag history

John Hetrick and Walter Linderer created restraint systems that used airbags. It is interesting that both acted independently of each other, and their inventions were created almost simultaneously and were very similar to each other. The patents were innovative in terms of protecting the health and life of the driver, but they also had some drawbacks. Modifications introduced by Allen Breed made the airbag faster, safer and more sensitive to impacts. The systems currently in use are based on his solutions implemented in the 60s.

The first airbags in the car

Immediately after the invention of the described security systems, General Motors and Ford became very interested in patents. However, it took quite a long time before the invention was efficient and effective enough to be installed in vehicles. Therefore, the airbag appeared in cars not in the 50s and not even in the 60s, but only in 1973. It was introduced by Oldsmobile, which produced cars of higher segments and luxury cars. Over time, it ceased to exist, but the airbag as a system survived and became almost mandatory on board every car.

When does an airbag in a car deploy?

Sudden deceleration after hitting an obstacle is interpreted by the safety system as a threat to the driver and passengers. The key in modern cars is the position of the car in relation to the obstacle. The reaction of the front, side, middle and curtain airbags depends on it. When will the airbag explode? For the airbags to deploy, the speed of the vehicle must be reduced sharply. Without this, the functional element cannot be started.

Will the old airbag work?

Owners of older vehicles may ask themselves this question. They often had an airbag in the steering wheel and on the dashboard. However, driving without damage does not allow the system to work for many years. Initially, car manufacturers specified that the airbag should be replaced every 10-15 years. This had to be associated with the risk of damage to the gas generator and the loss of properties of the cushion material itself. However, years later, they had to change their minds about it. Even old security systems will work without problems.

Why is the airbag almost 100% effective despite the years?

Materials affect this. The air cushion is made from a combination of cotton and synthetic and very durable materials. This means that even after many years it does not lose its tightness. What else makes it effective? Placing control systems and a generator under the elements of the car interior is a guarantee of protection against moisture, which at a crucial moment can have a devastating effect on the operation of the system. People involved in the disposal of airbags in old cars, say that the percentage of non-deployed copies is marginal.

Is it safe to deploy an airbag?

What is the most common fear of a person who has never experienced an airbag before? Drivers may fear that the handlebar's front cover, made of plastic or other material, will hit them in the face. After all, he must somehow get to the top, and the top of the horn hides him. However, airbags are designed in such a way that in the event of an explosion, the steering wheel cover is torn from the inside and deflected to the sides. This is easy to verify by watching the crash test video. So if you hit your face, don't be afraid to hit the plastic. It doesn't threaten you.

What else affects the safety of airbags?

There are at least two more things related to airbags that are worth mentioning in the context of driver and passenger comfort. The airbag has valves that allow compressed gas to escape. This solution was used out of concern for the health of the people in the car. Without it, the head and other parts of the body, under the action of inertia, would hit with a push against an extremely rigid gas-filled bag. It's more or less the same feeling when soccer balls are hurtling in your face.

Airbag comfort and activation time

Another important issue is the reaction of the system to a car hitting an obstacle. Even at low speeds of 50-60 km / h, the human body (especially the head) is rapidly moving towards the steering wheel and dashboard. Therefore, the airbag usually fully deploys after about 40 milliseconds. It's less than the blink of an eye. This is an invaluable help for a person moving sluggishly towards the solid elements of the vehicle.

Airbags deployed - what to do with them?

If airbags deployed in your car after an accident, you definitely have something to rejoice at. They probably saved you from serious bodily injury. However, when repairing a vehicle, it is also necessary to regenerate or replace the security system itself. Unfortunately, this procedure is not limited to installing a new pyrotechnic cartridge and pad. You also need to replace:

• damaged interior elements;
• plastics;
• safety belt;
• the steering wheel and everything that was damaged as a result of the activation. 

In OCA, such a procedure costs at least several thousand zlotys (depending on the car).

Airbag Indicator Light and Post Deployment Repair

Cars arriving in Poland often have an "interesting" accident history. Of course, unscrupulous people want to mask this information. They do not replace elements of the security system, but bypass the sensors and the controller. How? The airbag is replaced with a dummy, and in extreme cases with newspapers (!). The indicator itself is bypassed by connecting to the sensor, for example, by charging the battery. It is also possible to install a resistor that deceives electronic diagnostics and imitates the correct operation of the system.

How do you know if your car has airbags?

Unfortunately, in many cases it is not possible to verify whether anyone is engaged in such practices. There are only two exits for checking the actual presence of airbags in the car. The first option is to check with a diagnostic computer. If an unscrupulous mechanic did not bother to install a resistor, but only changed the connection of the controls, this will come out after checking the ECU. However, this is not always possible.

What if you absolutely want to check the condition of your airbags?

Therefore, the only 100% sure way is to disassemble the interior elements. That's how you get to the pillows. However, this is a very expensive service. Few car owners decide to take such a step just to check for airbags. However, only this method is able to give you complete information about the condition of the car.

In cars currently produced, the airbag is installed in many places. In the most modern cars, there are from several to dozens of airbags. They protect the driver and passengers from almost all sides. This is, of course, a recipe for improving the safety of the people inside. What is the disadvantage of this system? Often this is the noise created by the explosion and the rapid cooling of hot nitrogen. However, this is a trifle compared to the advantages of this element.