how to airbags work in car

how to airbags work in car

What are airbags and how do they work

The airbag is a passive safety device installed inside the steering wheel, dashboard or even the seats or roof of a car to protect passengers from impact in the event of a road accident.

An airbag is a device that uses an inflatable bag to absorb physical impact, and is often used to protect occupants in the event of a car accident.

Nowadays, along with seat belts, it is generally installed in passenger cars as a protective device for occupants, and there are also products for motorcycles.

Find out what are the characteristics of the airbag, its operation and the different types Since 1952, the year of its first official patent, the airbag has become a fundamental safety device and now fitted to any car you decide to buy, large or small displacement that is. Today we talk about airbags in the plural because you certainly have at least two of them on your car too. One for the driver, installed in the steering wheel, and one for the passenger, located above the glove box.

The airbag inflates when it senses a certain impact and prevents the occupant from hitting the steering wheel, dashboard, door, etc. The time it takes to deploy an airbag is instantaneous. When converted to speed, it can reach from 100km / h to 300km / h. Side airbags that not only absorb the impact from the front but also protect from the impact from the side and curtain airbags that cover the side window parts have become common.
The driver and passenger airbags are designed so that the sensor detects the impact and deploys when the vehicle hits from the front at a speed of about 30 km / h or more, so it operates at lower speeds. It may not be. Also, if the impact is transmitted only partially, or if the impact is dispersed or gradually transmitted, it may not be detected correctly and may not be deployed.

The airbag is a flat-shaped balloon that inflates instantly upon impact, escaping from the compartment in which it is stored. The main function is to prevent contact of the passengers’ head or face with the steering wheel and dashboard.

To avoid reducing the effectiveness of the airbag, it is essential to always keep seat belts fastened.

The airbag consists of a sensor that detects deceleration following the impact, a control unit that processes the signal and sends it to the detonator which subsequently ignites the substances contained in the explosive capsule and finally the bag made of synthetic material impermeable to gases.

At the moment of impact, an explosion occurs that inflates the bag in 30/50 thousandths of a second and protects the head and, partially, the chest of those sitting in front. Immediately after activation, the bag begins to deflate through the holes it is equipped with.

Once the airbag has come out of its seat to protect the occupants after the impact, it can no longer be used again but must be replaced with a new device.

Airbag warning light on

The correct functioning of the airbag is indicated on the dashboard by a red light that portrays a seated passenger with a seat belt and a front balloon. This always comes on when the car is started and then goes off shortly thereafter and thus indicates the perfect functionality of the safety system.

However, it may happen that this airbag warning light stays on or comes on suddenly while driving.

In this case, you can try to solve this problem by pulling over and switching off the engine in order to reset the system. But if this attempt does not bring benefits then it is advisable to contact a specialized workshop to diagnose the control unit and understand the reasons for the problem.

Airbag instruction sign. Caution airbag logo.

Airbag sensors

The collision or acceleration sensors mounted directly in the control unit or as satellites on the front or side of the vehicle are essential for the operation of the airbag.

These detect the sudden deceleration due to impact and send the signal to the control unit which, in turn, activates the detonator and consequently opens the airbag.

The airbag sensors must also be checked following the impact, to ensure that they have not been compromised in the impact. In this case, it will also be necessary to replace them in addition to that of the airbag.

Airbag type

airbag and horn icon on steering wheel

Currently, most passenger cars are equipped with airbags, but there are two types of devices that activate the ignition device in the event of an accident: “mechanical” and “electronic”. Older cars are fitted with “mechanical” airbags.

“Mechanical” is a mechanism in which the gas generator is mechanically ignited when the sensor detects an impact, and it cannot be intentionally operated except in an accident. It is extremely dangerous if it is activated when the vehicle is scrapped and the gunpowder is ignited, so it is necessary to remove the airbag unit before dismantling.

Relatively new cars are equipped with “electronic” airbags, which are the mechanism by which the computer determines that an impact is detected and the ignition system is activated.

Since it is possible to activate the ignition device by sending a command to the computer even in cases other than accidents, when dismantling a scrapped vehicle, first activate all airbags.

Side airbags

Side airbags have spread rapidly over the last few years and are intended to protect the occupants of the vehicle in the event of a side impact and offer adequate protection even in the event of the vehicle overturning.

Curtain airbag

Among the most popular side airbags are curtain airbags. These protect the heads of the front and rear passengers during a road accident and in the presence of transverse impact forces. Once exploded, the airbag is positioned between the passenger’s head and the window and also protects in the event of the vehicle overturning.

Collision cases where airbags may not deploy

・ Collision in which only a part of the car is extremely deformed
・ When hit diagonally
・ When the other vehicle hits the side of the own vehicle, the body of the other vehicle is greatly deformed or the own vehicle moves due to the impact, so the impact force generated at the time of the collision is dispersed and the airbag is released. If the sensor does not receive a shock that is worth opening
・ Collision that sneaks into the truck bed

Wear your seat belt properly even if you have an airbag

Lady fastening her own seatbelt inside of the car

Airbags are more accurately called SRS airbags. SRS is an abbreviation for Supplemental Restraint System, which only assists the function of the seat belt.
If the airbag is not fastened with a seatbelt, it will not be effective enough and may increase the risk. Looking at the fatal accidents when the airbag is deployed, the data shows that the mortality rate when the seatbelt is not fastened is about 15 times higher than when the seatbelt is fastened. There is also “Comprehensive Automobile Safety Information” (site address listed below). Also, even if you are wearing a seatbelt, do not put your face or limbs forward and take the proper seat position.

What happens when the airbag opens?

Airbags are one-time “disposable” and cannot be reused once activated. If the accident is so big that the airbag opens, it is possible that the car body has been seriously damaged.

For this reason, in general, when an airbag is activated, it seems that there are many cases where the vehicle is scrapped without repair. However, depending on the situation of the accident, it may be possible to repair the car without scrapping it.

Basically, airbags do not operate unless a major accident occurs, but in rare cases, they may malfunction due to a malfunction. Even if the car body malfunctions without major damage, the entire unit must be replaced.

Airbags are one of the safety devices to protect car occupants in the event of an accident and have helped prevent death and fatal injury.

Research and development are still underway, and it will continue to play an important role in saving people’s lives.