The airbag serves to slow the passenger forward in a collision in a matter of seconds. It is made of nylon fabric and is stowed in the dashboard, steering wheel, seat or door. A device sensor is installed there, which tells the pillow when it needs to be inflated. About what gas is filled with an airbag, the principle of its operation, as well as precautions when using airbags, this publication will tell.
Inflation starts at collision force equivalent to a collision with a wall at a speed of 16-24 km / h. Upon impact, a massive shift occurs that closes the electrical contact, after which the mechanical switch is activated. This informs the sensors about the accident.
The airbag pressurization system mixes potassium nitrate and sodium azide. Eventually gas is released, which inflates the airbag with an explosion .
Pressurization system similar to a rocket booster. It ignites solid fuel, which burns quickly, creates large volumes of gas, and they inflate the pillow. The pillow bursts out of its place in the blink of an eye, at a speed of 322 km/h. The gas is then dispersed through small holes in the chamber, deflating the cushion so that you can move.
The entire process takes 1/25th of a second, but extra time is required to prevent serious injury. The powdery substance that is released from the pillow is talc or cornstarch. It is used to keep the pillow flexible and to lubricate when the pillow is in its storage.
The main precautions that are associated with airbags.
From the first use of airbags, they were warned that airbags should be used in conjunction with seat belts. Seat belts were necessary because the airbags only worked in the event of a frontal match. In a side crash or skid, only seat belts will help. Although side airbags are now common, they are much more effective when used in conjunction with seat belts.
The strength of the pillow can hurt someone close to it. The most dangerous are 5-8 cm of airbag inflation. It should be located 25 cm from the pillow. If the distance from the center of the steering wheel to the chest is less than 25 cm, the driver's seat must be adjusted. Lower the seatback slightly. Move the driver's seat back so that you can comfortably reach the pedals. You also need to make sure that the pillow is "aimed" at the chest, and not at the neck or head.
For children, the rules for using airbags are different.
If a child is not wearing a seat belt, or is sitting close to an airbag, the airbag could injure or kill the child.
Conditions necessary for the safety of the child:
- Children under 12 must ride in special child seats that are appropriate for the child's age.
- Infants under 1 year of age who are in a child seat should not ride in the front seat of a vehicle where there is an airbag on the passenger side.
- A child over 1 year old who is forced to ride in the front seat must be seated in a forward-facing child seat or booster cushion, or using a shoulder or knee belt. The seat should be reclined as far as possible.
The rate of a chemical reaction is proportional to the concentration of the reactants: the higher it is, the more often the molecules collide and the faster the reaction proceeds. Similarly, the frequency of accidents is proportional to the concentration of cars on the roads, which is steadily increasing. Accordingly, the number of accidents is also growing. The most dangerous occur in a head-on collision. Is it possible to protect the driver and passengers at the same time? One of the simplest and most reliable inventions is seat belts, which have saved many lives. But if the speed of the car during a head-on collision is high, they do not save either: the belt delays the body, and the head continues to move forward by inertia, which leads to damage to the cervical spine. This injury is usually fatal.
Twenty years ago, chemists from leading automotive corporations developed a new way to protect motorists - an airbag. It is a bag made of durable polyamide fiber and when folded it takes up so little space that it can be stowed away in the steering wheel post. In a head-on collision, the bag inflates almost instantly and gently takes on the forward movement of both the body and the driver's head, thereby saving his life. If by the end of the 80s only one out of 15 cars produced in the USA was equipped with an airbag, now almost all cars have two of them - for the driver and for the passenger.
How does this device work? Since the accident counts in thousandths of a second (at a speed of 100 km / h, the car travels 10 cm in just 3 milliseconds), no mechanical compressors or compressed gas cylinders will have time to inflate the bag. What remains is the explosive decomposition of the chemical compound with the release of a large volume of gas. Chemists needed to find such a compound, and the rest was a matter of technology. There were few options. We settled on the decomposition of sodium azide, a salt of the highly explosive and highly poisonous hydrazoic acid HN3. Although this acid is weak (caacetic), its aqueous solutions have such a strong oxidizing effect that a mixture of HN3 and HCI dissolves gold and even platinum. Heavy metal azides (copper, silver, mercury, lead, and others) are highly unstable compounds that explode upon friction, impact, heating, and exposure to light. An explosion can occur even under a layer of water! Lead azide Pb (N3) 2 is used as an initiating explosive, with the help of which the main mass of explosives is undermined: only two tens of milligrams of this substance is enough for this.
Sodium azide itself does not explode, but is poisonous; its highly diluted aqueous solutions are sometimes used as a preservative for biochemical preparations.
It all works like this. In the event of a collision, the sensors installed in the vehicle transmit a signal to the microprocessor. He assesses the situation; if the vehicle speed exceeded a certain value (usually 35 km/h),
the microprocessor turns on the electric fuse and starts the azide decomposition reaction. As a result, a bag containing about 70 liters of nitrogen is inflated in front of the person. This will save his life even in cases that were previously considered hopeless. In the latest cars, you can even adjust the speed of filling the bag with nitrogen, depending on the weight of the driver and his exact location in the cabin.
However, safety bags, although proven to be effective, pose environmental problems. After all, most cars end their life without ever experiencing a head-on collision. And in landfills, instead of relatively safe piles of rusting metal, foci of toxic substances can form. One way to combat this is to use tablets instead of powder that can be removed. Another way is to search for chemical compounds to replace sodium azide.
Airbag (airbag) is one of the passive safety elements in modern cars. Their presence is an important factor ensuring the safety of the driver and passengers. Airbag in translation from English means "airbag", hence the Russian name arose - an airbag, which we are all used to using.
Airbags have saved thousands of lives since they were mass-installed in vehicles. The idea of the Airbag system is simple: the airbags inflate quickly enough to protect the human body in the event of an accident. But how do they do it so fast?
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The device and principle of operation of airbags
The secret of instantaneous filling of airbags actually lies not so much in the pillows themselves, but in a special device - a gas generator. This is the most technically complex part in the entire Airbag system.
The gas generators used in airbags can inflate it about three times faster than you can blink. At the end of the article watch the video about how the airbag is arranged, and what stages of production it has to go through before being installed on a car.
The principle of operation of airbags is quite simple. They are activated on impact when the vehicle speed exceeds 20 km/h.
- In the event of a collision with an obstacle, one or more special sensors are triggered. These sensors can be installed at the front, rear and sides of the vehicle.
- The signals from the sensors are processed by an electronic control unit (ECU) that controls the operation of the Airbag system. Under certain conditions (for example, a strong frontal or oblique impact, running into a high curb, a hard fall after a jump, etc.), the ECU commands the airbags to deploy.
- Based on the programmed algorithm, the control unit decides on the need to deploy the airbags and transmits an electrical signal for execution.
- This signal enters the airbag gas generator, and a pyrotechnic charge is triggered in it (the squib fires).
- As a result of the triggering of the squib, the sodium acid contained in the gas generator burns out, releasing a significant amount of gas (nitrogen), which enters the Airbag and instantly opens it.
Airbags are made from nylon fabric similar to parachute fabric. It has holes through which the gas after inflating the pillow leaves it in just 0.3 seconds. Rapid deflation is necessary because as air is released from the air bag, it becomes softer.
A gas generator is attached to each airbag during the manufacturing process, after which it is rolled up into a compact package (small enough to fit in the steering wheel or in the passenger side dash panel). In this case, the gas generator for the driver's airbag is additionally placed in a rubber ring, in which it plays the role of a balancing weight.
Airbag Inflator Device
Since drivers and passengers come in different sizes, engineers at one time wanted to come up with an Airbag generator that could regulate the amount of gas. Early airbags could not change their inflation rate in relation to the size and position of a person, or the force of a vehicle collision.
Therefore, the designers came up with a "smart" generator - it has two squibs instead of one. One of them releases gas only by 80 percent (this is enough for a “soft landing”). But if that's not enough, a second squib triggers a refill, and the remaining gas fills the Airbag and makes it stiffer.
A typical driver's airbag inflator consists of the following main parts (refer to the illustration above):
- Housing with combustion chambers;
- Charges #1 and #2 from sodium acid tablets;
- Auxiliary charge to ignite charge #1;
- Two pyrotechnic cartridges for igniting charges;
- Metal filter.
So what happens in the gas generator when the Airbag is triggered?
- The igniters installed in the airbag inflator contain a material similar to gunpowder. When they receive a signal from the electronic control unit, they work, generating heat and high pressure.
- From the operation of a pyrotechnic cartridge in the gas generator housing, special sodium acid tablets (charge) located there light up. These pellets, when burned, release a hot but harmless nitrogen-based gas that deforms the alternator case and leaves it filling the Airbag.
- Before entering the airbag, nitrogen passes through a special metal filter that removes particulate matter formed during the combustion of the charge and cools the gas.
- When electricity is applied to the squib #2, it ignites the second charge. The gas generated during the combustion of the charge lifts the cap of the chamber of the stage #2 and inflates the airbag through the combustion chamber of the first stage.
From the moment the car gets into an accident until the airbag is fully inflated, no more than 30 milliseconds pass.
Types of car airbags
There are three main types of airbags most commonly used in cars:
- Front airbags- are installed in the steering wheel for the driver, and on the right side of the front panel of the car for the passenger. Such airbags are found in almost all foreign-made cars and in some domestic cars.
- Side airbags- in case of an accident, they protect the human chest, abdominal cavity and pelvic bones. These airbags are most often built into the backs of the front car seats.
- Curtain pillows(head airbags) - designed to prevent head injuries due to side impacts. Automakers install these airbags in the roof area, either front or rear, or between the B-pillars.
Also on some car models you can find knee airbags and even a central airbag (between driver and passenger). But these types of airbags are much less common than the first three, and mainly on premium car brands.
Since airbags have become such an important part of the design of a modern car, engineers are constantly looking into the possibility of testing their operation. German experts, for example, have developed and systematized a number of tests that take into account climatic factors and vibration, extreme temperature changes and various operating conditions of the device.
Manufacturers guarantee the perfect operation of airbags, because, compared to the environment they create in the laboratories, the real situations in which the car is operated can be called very gentle.
Airbags serve for a long time and reliably, not only thanks to the tests that precede their serial introduction, but also due to the perfection of the design, which itself monitors the maintenance of the Airbag system and eliminates the possibility of aging and wear of the fabric.
- industrial gas, which, in addition to other useful functions, also serves to save people's lives in road accidents. If necessary, it is he who quickly inflates the airbag.
An inflatable car airbag, or, as it is also called "airbag", is needed in order to extinguish the sudden impact energy. This traumatic energy manifests itself when a heavy, high-speed car collides with another vehicle or an immovable obstacle.
In this case, the driver and passengers of the car can be injured by glass fragments or any objects in the car. The pillow protects them from injury. Airbags have long been an almost indispensable part of any modern car. There can be from one to ten pieces in one machine.
Where and when did airbags begin to be used?
Back in the forties of the twentieth century, some aircraft were equipped with devices in their idea similar to airbags. In the fifties, patents began to be filed for various versions of this invention. The very first of these was a 1953 patent. It wasn't until twenty years later that the airbag became a safety feature in a production car.
Walter Linderer, an inventor from Munich, created the prototype of modern car airbags by fixing a bag on the steering wheel that was supposed to be inflated with air. Car manufacturers noticed and appreciated this invention. Unfortunately, in this form it was not possible to apply it for mass production of machines. No compressor could handle the difficult task of pumping enough air into an airbag in twenty milliseconds.
Therefore, in the future, it was proposed to use the energy of gases that are formed during the combustion of fuel. Burning rocket fuel in such conditions led to the explosion of the pillow itself and the entire car. After these experiments, they began to use gaseous substances that are released during the combustion of a “cartridge” or “tablet” of sodium azide. These substances are less of a fire hazard.
How are airbags used and filled now?
Such a pillow is a complex multi-component system. It includes the actual pillow, made of nylon. For this, a material is used, the thickness of which is from 0.45 to 0.55 millimeters. To enhance the tightness, nylon is coated with a layer of silicone or rubber. The gas generator is needed to fill the tank with gas. Impact sensors bring the pillow into working condition. The most modern and advanced systems are also equipped with an electronic control unit.
The gas generator is a squib. Solid fuel, NaN3 - sodium azide, when burned, releases a lot of gas, which quickly inflates the airbag. The burning of this substance occurs very quickly, but there is no explosion. 45 percent of the mass of combustion products is nitrogen. The remaining 55 percent is carbon monoxide, carbon dioxide, water vapor and particulate matter. The resulting gases and vapors are filtered before getting inside the pillow. As a result, only .
The time to completely fill the pillow in this case is from 30 to 55 milliseconds. After that, it remains in the expanded state for about a second. Harmless to humans, nitrogen through special holes is released into the car interior. The pillow then deflates, making room for the breathing and movement of the person it protects.
An electrical impulse comes from the shock sensors to the squib or from the electronic unit and turns it on. In modern cars, the response of such sensors depends on the speed of the car, the angle of impact and the nature of the obstacle. Sensors, usually at least three copies, are installed in the passenger compartment and its doors. In the most airbag-equipped cars, there can be up to ten of them. Electronic systems are equipped with a separate capacitor, which, if necessary, will provide energy for signal transmission from the sensor to the squib.
Pros and cons of old and new car airbag fillers.
The fillers in early prototype car cushions did not provide the necessary safety for drivers and passengers. Inflating them with air is too slow. Filling the pillow with gas generated during the combustion of explosive substances exposes people's lives to even greater danger.
Some airbag manufacturers use nitrocellulose as fuel. Its use does not require the installation of a filter. In addition, it will take less of this substance to fill the pillow. The gas obtained from eight grams of nitrocellulose and fifty grams of sodium azide fills the same volume.
Sodium azide and nitrocellulose, modern airbag fillers make it possible to improve their protective properties. Unfortunately, nitrocellulose, which is the basis of smokeless powder, is explosive. Therefore, its use is not widely used. The most commonly used is sodium azide.
The number of airbags with different purposes and placement in the car is constantly increasing. Developers offer new options to better protect people in the event of an accident. New, more sensitive sensors help the airbags deploy faster. The pillow deploys fully within twenty milliseconds.
Such sensors are able to distinguish the strength, nature and direction of impacts. Now they are able to turn on the squibs of certain pillows. Inside the adaptive pillows, the internal pressure is regulated, as well as, depending on the situation, the degree of their opening. The necessary pressure is maintained in them for ten seconds, this protects people from injury when the car is overturned or in a re-collision.
The squibs themselves have become safer for human health. More advanced filters do not let poisonous gas and harmful particulate matter into the pillow and further into the cabin.
Interesting facts about airbags.
If you turn to the famous diaries of Leonardo da Vinci, it may turn out that the concept of an airbag is much older than is usually assumed. One of the drawings, which is in the archival materials of the Royal Library of Turin, shows a kind of device. The figure of a man on it is surrounded by leather furs filled with air. As follows from the caption to the figure, their purpose is to protect a person falling from a height to the ground or water from bruises.
Sodium azide is a toxic substance. The symptoms of poisoning are similar to those of cyanide poisoning. Large doses of this substance can lead to death.
In order for airbags to perform their function well, they must be replaced at least every ten years.
Nowadays, airbags are being actively developed not only for motorcyclists and cyclists, but also for pedestrians. The protective cushion for cyclists is something like a rapidly inflating helmet. It should protect the head of a person who has fallen from a bicycle from injury.
Airbags, whose task is to save pedestrians, are located outside the car. There are two of them: one covers the entire front of the car, the other protects the passenger's head from hitting the windshield.
Around 1.2 million people die in car accidents worldwide every year. Europe in terms of the number of fatal accidents ... Last but not least, the technical properties of the car, its "stuffing" affect the outcome of the accident. Therefore, both manufacturers and motorists are puzzled by the search. As tests show, the airbag of the driver significantly reduces the risk of his death. Just imagine, the cars collided head-on and in such a situation the driver gets 20-25% more chances to survive. About how exactly car pillows can protect a person, and which of them are the most effective - we'll talk in our article.
Idea in a bag
How it works?
What is the principle of operation of airbags? This mechanism consists of several parts. The first is the pillow itself. As a rule, it is made of nylon with silicone or. The volume of the driver's pillow reaches 80 liters, and the passenger one - up to 130.
Video on how airbags work:
The second is shock sensors and inert sensors located in front and on the sides of the body. The third is a box with gas or a pyrotechnic cartridge. In the "box" is a special "explosive" mixture. The fourth is an electronic processor.
Life in seconds
So, all these components are needed in order to react with lightning speed and “open the parachute”.
The principle is this: at the moment of impact, at least one is triggered. It reacts to pressure or to an unjustified increase in speed. Along the chain, the sensor sends the corresponding signal to the microboard. The processor is triggered and gives a command to open the pyrotechnic cartridge. At this moment, a mini explosion occurs, a surge of nitrogen and the pillow, filling with gas, jumps out into the cabin.
The pillow, when opened, covers the driver with itself and so softens the blow. Also, it is highly likely that she will not allow a person to fly out through.
All this happens at lightning speed, takes some fractions of a second (on average, about 0.25 seconds).
Plus and minus
But the work of the pillow does not end there. Having fixed passengers, it is automatically blown away. Thus, the "bag" will not become an obstacle and will not pinch anyone, making it difficult to get out of the car.
Although there is a drawback here: the pillow effect is one-time. And if at the time of the accident, for example, a paired phased collision occurs, then the “bag” will work only at the first “bang”.
"Inflatable" assortment
There are also different types of airbags. Some are designed to protect the driver. Other - . There are "bags" for the cabin and those that are attached to the outside of the car to mitigate the effects on pedestrians. Separately, devices have also been developed for owners of motor vehicles, so that when they “meet” head-on, they do not allow the rider to fly forward.
Pillows in the cabin can be side and front.
At the front…
Most often, frontal devices are now used, creating a block between people sitting in front and the front of the car. These pillows are also built into the panel opposite the passenger seat.
Keep in mind that if the passenger seat in your car is provided with a front airbag, then the passenger must be extremely careful. The main rule: do not hold anything large (not even a bag) and do not press the panel with your knees. Otherwise, when opening, you can get serious injuries ...
... and on the side
But it becomes possible to install "air bags" in the backs and in the doors on the side. This is the horizontal protection, which so far is most often found only in expensive models.
Such mechanisms are triggered by a powerful push to the side of the body. Such pillows are called "curtains" due to the fact that, when opened, they are located in the windows. This position allows you to protect the heads and necks of passengers.
Reasonable Defense
The process does not stand still and the development of new generation "bags" is already underway. For example, some options are so independent and intelligent that they are able to make decisions about limiting the volume when opened. Such a self-stop control. This is an opportunity to individually select the “bloating” parameters depending on the physiological characteristics of the passengers and the position of their seat belts. In this way, many injuries can be avoided. In order for the device to carry out such an analysis, a special sensor mechanism is provided.
Safe security
Despite all the know-how, in order for the “air bags” to work correctly, not only mechanisms, but also people must try. We have already talked about the seat belt. So once again - this is not discussed, it must be fastened!
Video on how airbags are made:
It is also desirable to take straight, even postures inside the salon. The option to go reclining is not suitable.
Also, do not close or seal the openings for the pillows to fly out with “pretty things”. Especially pay attention to the device in the steering wheel - keep your hands on the side, and not on top of the steering wheel.
Separate item -. Toddlers must ride fastened in special children's "transportations" that are mounted on the back sofa of the car.
Be careful not to let technologies invented for human safety lead to the opposite effect. Do not forget for a moment that your car has "inflatable" pillows and let this be an excuse to drive even more carefully, and not "rush into speed with your head."
