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Airbag: types, principle of operation, sensor, errors, replacement

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Airbag: types, principle of operation, sensor, errors, replacement
Airbag: types, principle of operation, sensor, errors, replacement

The first car models that rolled off the assembly line offered little to no crash protection. But engineers constantly improved the systems, which led to the emergence of three-point belts and airbags. But they did not come to this right away. Nowadays, many car brands can really be called reliable in terms of safety, both active and passive.

Some information about pillows

We can safely say that the first attempts to mount an airbag in the design of a car were made in 1951. But everything turned out to be not so simple. The catch was that at the time of the collision, the airbag should fire in 0.02 seconds. But no compressor can cope with such a task. Then engineers began to use the energy of gases, which was released during the combustion of fuel. The first experiments were carried out with rocket fuel. But there was no success. Tearing not only pillowssecurity, but also the car. Then they began to use sodium azide.

curtain in the side pillar of the car

This approach gave the best result. However, cars equipped with sodium azide tablets, or rather their owners, became owners of explosives. Consequently, each driver took written responsibility and committed to changing the device every few years. Actually, all these attempts to introduce airbags into the car gave a serious impetus to the improvement of the design.

Design and principle of operation

Officially, the patent for the invention of airbags belongs to Mercedes since 1971. But this does not mean at all that other large automobile firms did not conduct their own developments. As for the design, everything is quite simple. A nylon pad 0.4-0.5 mm thick and a gas generator are combined as a single unit. The design includes a shock sensor, and the latest cars are equipped with an electronic control unit.

maximum passenger protection

The gas generator, also known as a squib, contains solid fuel. When it burns, a large amount of gas is released, which fills the nylon pad. The latter is often wrapped in rubber for tightness. The same sodium azide is used as fuel, it is considered poisonous, but when burned, it forms nitrogen. The high rate of ignition and combustion of fuel is not explosive. It is believed that the optimal deployment time for airbags is 30-55 milliseconds.

Severaldesign features

A filter element is installed in the airbag. It is designed in such a way that only nitrogen enters it. It is worth noting that the airbag is in a fully inflated state for only 1 second. The design provides special openings for the release of gas into the cabin. This was done in order not to strangle the driver and passenger. In recent years, many automakers have replaced sodium azide with nitrocellulose. The latter needs much less to effectively operate the pillow, about 8 grams versus 50 sodium azide. In addition, it became possible to remove the filter element.

seat cushion

Airbag sensor - electrical. Responds to pressure and acceleration. It is the main signal for the operation of the airbag. Modern cars are equipped with a large number of sensors installed in various places of the car: in front, on the side, and even in the headrests. They not only react to speed, but also determine the angle of impact. Provided by the manufacturer and instant failure of the battery. For this case, the pillow has a capacitor, the charge of which is enough to trigger the security system.

Airbag specifications

Where are the airbags in the car? It all depends on the configuration, but they must be in the steering wheel of the driver and on the dashboard of the front passenger. They can also be located on the side racks, head restraints, etc. As for the performance characteristics, in most cases the volume of the pillow on the driver’s side reaches 60 liters, andpassenger - 130. This suggests that literally in 0.02 seconds the volume of the cabin decreases by about 200 liters. As a result, high pressure is created on the membranes. The pillow meets the driver and passenger at a speed of about 300 kilometers per hour. If people are not fastened, then the inertial movement towards them can lead to sad consequences, even death.

side impact protection

As noted above, from 2 to 6 pillows can be installed in a car. If all of them work, then noise up to 140 dB is created. This is extremely dangerous for the eardrums. Therefore, manufacturers have made it so that only the right airbags work and at different times. For example, the driver's airbag deploys after 0.02 seconds, and the passenger airbag inflates after 0.03. Most cars after 2000 are equipped with sensors installed in seat belts and seats. Therefore, if the driver is not wearing a seat belt, then the airbag will not work.

Airbag instructions

There is no manual as such. But there are a few simple manufacturer's requirements that are recommended to be observed. They look like this:

  • use seat belts for maximum protection;
  • the passenger must sit straight, it is not allowed to lean on the armrest, legs on the dashboard, etc., as this can lead to fractures and even death;
  • passenger must be in a seated position, so the seatback needs to be adjusted beforehand;
  • notit is allowed to apply stickers and other items on the working area of ​​the airbag, as this leads to a distortion of its geometry and slows down the opening;
  • hands on the steering wheel should be at the side.
airbag icon

Actually, following a few simple rules will lead to maximum efficiency of the passenger and driver airbags and increase the chances of surviving a serious accident.

Airbag upgrade

Every year, more and more advanced airbags are produced. Currently, there are about 10 varieties of them. They are front and side. The former are responsible for the safety of the head and torso, and in some cases the legs of the driver and passengers. They work on a frontal impact. Side pillows are made in the form of curtains and pipes and protect the head and chest. The latest development of the company "BVM" - side tubular airbags, which are inflated for 7 seconds to protect against repeated overturning of the car. And on the American market, the "seven" is equipped with an airbag for the legs in front of the seated passengers. The Volvo company, famous for its safe cars, has begun developing belts and pillows designed specifically for pregnant women. The French company Renault is also active in developing knee airbags and security systems for rear passengers.

Replacing airbags

Many motorists believe that the system is completely maintenance-free and there is no need to intervene.needs, but that's not the case. Pillows manufactured in 1990 are recommended to be replaced after 10 years. Somewhat later, Mercedes extended the term to 15 years. It is advisable to carry out testing and replacement at an authorized dealer, as complex electronic work, etc. is required.

external airbags

The car is also equipped with a diagnostic system. If the icon on the instrument panel does not go out after a few seconds when the ignition is turned on, then this indicates a malfunction in the system. The airbags may need to be replaced or serviced in some way. When purchasing a used car, you can safely count on the fact that the pillows in it are already "shot", although the error may not burn. Therefore, at the service station, such moments should always be checked.

Triggered injury hazard

In most cases, the fault lies with passengers who do not comply with safety regulations. For example, on the sun visor in most cars it is written that children under 12 years old can be killed with a pillow. This is due to the fact that she shoots the child in the head, since growth usually does not exceed 150 centimeters. Another typical situation is the deployed child seat in relation to the pillow. Often such a mistake costs the life of a baby. Therefore, child seats are recommended to be installed in the center of the rear sofa, as there is the safest area in the event of an accident. Usually there are asterisks next to the airbag or SRS inscription. They signal the injury risk of the pillow. The more stars (maximum 5), thebetter, the minimum number of them indicates a high risk of damage.

What should not be forgotten?

A failed airbag sensor or a faulty squib can be fatal. Incorrect passenger or driver position or a seat belt not fastened can cause death in even a minor accident. Fortunately, modern cars contain an increasing number of electronic active and passive safety systems designed to protect the car's occupants. But if an airbag error appears on the dashboard, it is recommended to fix it as soon as possible.

pillow in the steering wheel


The American company "Ford" is actively working on the creation of airbags for pedestrians. After all, studies have confirmed high mortality even in a collision at a speed of 40 kilometers per hour. It is planned to install two pillows. One will be large - it covers the radiator grill and hood, and the second is small - it is installed near the windshield. The latter should protect the pedestrian's head. The car will be equipped with special sensors that calculate the distance to the object. They will work immediately before the collision. According to many experts, this approach will significantly increase the survival rate of pedestrians upon impact. But this does not mean at all that you do not need to look around before entering the roadway.

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