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Modern cars are equipped with a number of systems and solutions to enhance safety in the event of a collision. One of them are airbags – used in various models of cars since the 1970s. How does the airbag system work and what affects its efficiency?
Although an airbag did not become part of the basic equipment of cars until around the 1980s, work on such systems began much earlier. Initially, such solutions were intended primarily for use in aircraft – a patent for this invention was granted as early as 1920. Interestingly, two dentists are responsible for the development of the first airbags. However, with the development of automobiles and the advent of increasingly powerful power units, there was a need for additional protection for drivers and passengers, resulting in the development of airbags for use in cars in the early 1950s.
The first automotive airbags were based on a mechanical design. A collision or the pressing of an appropriate button by the driver triggered the activation of a spring, whose task was to unlock the supply of compressed air. Such a mechanism, however, was characterized by being too slow, which led to the development of new solutions using electronics or chemical reactions. Since the 1970s, airbags began to be increasingly used in vehicles, now becoming one of the basic components of a car.
How does the airbag system work? In most modern vehicles, its functioning is based on a combination of the use of an electronic control system (ACU – Airbag Control Unit) and a gas generator. Contrary to its name, airbags are not actually filled with air – instead, chemical compounds such as sodium azide (NaN3) are used to provide a very rapid increase in pressure. The gas is "fired" at speeds as high as approx. 300 km/h. Sodium azide itself is a poisonous substance, but it is quickly broken down into sodium and nitrogen. Due to its toxicity, however, research is underway into the use of other substances, including chemical compounds involving strontium.
The ACU's task is to determine the appropriate moment of activation according to data collected by a series of sensors that monitor, among other things, the performance of the braking system, current acceleration or pressure on various parts of the vehicle's structure. When a strong enough collision occurs, the ACU activates the gas generator. This in turn is activated by electrical conductors wrapped in flammable material. The result is an explosion that fills a polyamide or nylon/cotton bag with gas.
The entire process takes only a few dozen milliseconds – ensuring that the airbag activates in the shortest possible time is crucial to ensure safety and protect the driver or passengers from a windshield collision. As soon as the airbag is activated, the gas (decomposed into its basic components, namely nitrogen and sodium) is released through special holes so as not to cause additional injuries after the impact.
See also: EURO NCAP rating score – how does crash test work?
Activating the airbag without a seatbelt being fastened can lead to a variety of dangerous injuries in the event of a collision – including, but not limited to, a broken neck. For this reason, in many cars, the airbag system is deactivated when the driver or passenger is not using a seat belt. It is worth noting that this is not a rule: in some models the ACU system is on at any time, while in others it may be activated according to information from the seat occupancy sensor. However, always remember to fasten your seatbelt – it is a key safety mechanism that can save your health and life in the event of an accident.
See also: The impact of the correct position behind the steering wheel
Like other systems used in automobiles, airbags are subject to various failures. In some situations, the failure of this component can result in a lack of activation at the time of an accident or the airbag exploding on its own without a collision. The primary signal that alerts you to potential problems with this component is the airbag light on the dashboard – you should address this issue as soon as it lights up.
The answer to this question depends to some extent on the year of manufacture and the country of origin of the car. In the European Union, airbags have been mandatory since 2009, while in the United States they have been mandatory since 1998. For vehicles imported from other regions or manufactured earlier, it is an optional feature. When buying an older car, it is therefore worth checking the presence and operability of airbags.
See also: Elements of passive car safety systems
Safety is a key issue when driving a car. To ensure adequate protection for the driver and passengers, not only airbag systems should be applied, but also other solutions related to the car's structure. Knauf Automotive offers lightweight and durable plastic components, made e.g. from EPP (expanded polypropylene), that effectively support the operation of other safety systems – including airbags.
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Airbags are inflatable cushions built into a vehicle that protect occupants from hitting the vehicle interior or objects outside the vehicle (for example, other vehicles or trees) during a collision.
The instant a crash begins, sensors start to measure impact severity. If the crash is severe enough, the sensors signal inflators to fill the bags with gas in a fraction of a second.
Airbags don’t typically require maintenance unless they deploy in a crash. In that case, they must be replaced at a repair shop that uses original equipment manufacturer (OEM) replacement parts to ensure that the new airbag is not counterfeit. Counterfeit airbags may fail to deploy or release metal shrapnel during deployment.
Since the 1999 model year, the federal government has required automakers to install driver and passenger airbags for frontal impact protection in all cars, light trucks and vans.
Front airbags are designed to inflate in moderate-to-severe frontal crashes to prevent a person’s head and chest from contacting hard structures in the vehicle.
They offer the most protection when occupants are wearing safety belts and sitting properly in the seat but are designed to provide protection for all occupants.
Newer airbags have a safety belt sensor and use an algorithm to decide whether to deploy the bag in a given crash, depending on whether people are using safety belts.
For unbelted occupants, a front airbag will typically deploy when the crash is the equivalent of an impact into a rigid wall at 10-12 mph. For belted occupants, most airbags will deploy at a higher threshold — about 16 mph — because the belts alone are likely to provide adequate protection up to these moderate speeds.
Front airbags may deploy to help protect occupants in side impacts if there is sufficient forward movement during the crash.
The driver airbag is located in the steering wheel. The passenger airbag is located in the dashboard.
Front dual airbag system Knee airbag (BMW)Some manufacturers provide supplemental knee airbags, mounted lower. Knee airbags are intended to distribute impact forces to reduce leg injuries. They may also help reduce forces on an occupant’s chest and abdomen by controlling movement of the occupant’s lower body.
Head- and chest-protecting side airbags are designed to inflate in side crashes to prevent people’s heads and chests from contacting intruding parts of vehicle side structure, a striking vehicle or an object such as a tree or pole. Side airbags cushion and spread the load of impacts to prevent any part of the body from sustaining concentrated impact forces.
A head-protecting side airbag is particularly important because it may be the only thing between the occupant’s head and the striking vehicle, since window glass can shatter in a crash.
Because of the small space between an occupant and the side of the vehicle, side airbags must deploy very quickly, typically within the first 10-20 milliseconds of a side crash. Deployment thresholds can be as low as 8 mph for narrow object crashes (e.g., trees and poles) and 18 mph for the more widely distributed side impacts (vehicle-to-vehicle crashes). Side airbags also deploy in certain types of frontal crashes.
A federal regulation on side-impact protection requires a certain level of head and torso protection for all occupants. While it doesn’t specifically mandate side airbags, the required protection is typically achieved with them. As of the 2014 model year, virtually all new passenger vehicles must comply with this regulation. As a result, the vast majority of passenger vehicles come with side airbags as standard equipment.
A head-protecting curtain airbag is often the only barrier between the dummy’s head and the striking vehicle.Side curtain airbags can be designed to deploy in a rollover crash. Sensors that measure a vehicle’s sideways movement and tilting can detect if a rollover is about to occur, triggering deployment. These airbags typically inflate within the first 10-20 milliseconds of a rollover crash and can remain inflated longer than regular side curtain airbags (10 or more seconds) to protect during multiple-roll crashes. They typically cover the window opening and inflate more stiffly to prevent ejection of the occupant.
The government doesn’t specifically require side curtain airbags with this capability, but automakers have been using them to meet a requirement that all 2018 or newer vehicles prevent occupant ejection through side windows.
A side curtain airbag used to meet the federal safety standard to prevent occupant ejection remains inflated for more than 10 seconds, covering multiple rolls of the vehicle, and keeps occupants contained inside.Click here to get more.
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