Speed chemical reaction is proportional to the concentration of the reagents: the higher it is, the more often 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 growing. The most dangerous ones occur during a head-on collision. Is it possible to protect the driver and passengers? One of the simplest and most reliable inventions is seat belts, which have saved many lives. But if the speed of the car in a frontal collision is high, they will not help either: the belt holds the torso, and the head continues to move forward by inertia, which leads to damage to the cervical spine. This injury is usually fatal.
About twenty years ago, chemists from leading automobile corporations developed new way protection of motorists - airbag. It's a bag made from durable polyamide fiber, and when folded, it takes up so little space that it can be tucked into the steering wheel column. In the event of a frontal collision, the bag inflates almost instantly and gently absorbs the forward movement of both the driver’s body and head, thereby saving his life. If by the end of the 80s, only one out of 15 cars produced in the United States 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 count in an accident is 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 stopped at the decomposition of sodium azide - a salt of the very explosive and very poisonous hydronitric acid HN3. Although this acid is weak (caacetic acid), its aqueous solutions have such a strong oxidizing effect that a mixture of HN3 and HCI dissolves gold and even platinum. Azides of heavy metals (copper, silver, mercury, lead and others) are very unstable compounds that explode upon friction, impact, heating, or exposure to light. An explosion can occur even under a layer of water! Lead azide Pb(N3)2 is used as an initiating explosive substance, with the help of which the bulk of the explosive is detonated: only two tens of milligrams of this substance are 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, sensors installed in the car 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 igniter 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 late-model 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 salon.
However, safety bags, although proven to be effective, create environmental problems. After all, most cars end their lives without ever experiencing a head-on collision. And in landfills, instead of relatively safe piles of rusting metal, pockets of toxic substances may form. One way to combat this is to use tablets that can be extracted instead of powder. Another way is to search for chemical compounds to replace sodium azide.
Safety in a new car is an integral part, not an option. More and more new types of systems and technologies are being developed. Let's consider the principle of operation, type and design of airbags.
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An airbag is now much more often in demand as an option than, for example, an air conditioner or a modern audio system. The main purpose of airbags (in cars referred to as airbags) is considered to be to soften the impact of passengers and the driver on the steering wheel, other parts of the body, and windows. As a rule, it is used with seat belts. The security system was first introduced in 1953 when Walter Linderer published his patent.
Types of car airbags
As a rule, modern cars have several airbags. Previously, only a driver's airbag was installed, but later they added one for the front passenger. In current models they are installed around the entire perimeter, in different places salon Pillows are divided by type depending on their location. The first are the front airbags, followed by the side airbags, head airbags, center airbag, knee airbag and pedestrian airbag. The latter option is installed externally, between the hood and the windshield.
Frontal
They were first used on Mercedes-Benz cars in 1981. As a rule, these are front airbags for the driver and passenger. In turn, the passenger side can be turned off at will. Often in modern cars, the design provides for two-stage or multi-stage operation. It all depends on the complexity of the accident (usually adaptive airbags). According to all the rules, the driver's airbag is installed in the steering wheel, for the front passenger - in the upper part of the front panel.
Side airbags
The main purpose of side airbags is to reduce the risk of injury to the pelvis, chest and abdominal cavity. As a rule, a side impact is one of the most unpredictable and painful. Volvo first used side airbags on its cars in 1994. This type of pillows was installed as an optional option to the main front ones.
Typically, the location of the side airbags is considered to be the back of the front seat. Although in modern cars you can also find them in the backs of the rear seats. Airbags with a two-chamber design are considered the highest quality. Their lower part is more rigid to protect the pelvis, and the upper part is soft to protect the chest.
Curtains or head pillows
Judging by the name, their main purpose is clear. In the list of car manufacturers they are also listed as curtains. In the event of a side impact, the curtains will protect your head from hitting the door glass. The very first this technology used by Toyota in 1998.
Depending on the model of the car, it can be located in the front part of the roof, also between the pillars and on the rear part of the roof of the cabin. Protection is provided for front and rear passengers.
Knee
The name itself speaks volumes about its purpose; protecting the knees and shins from injury is very important in the event of a collision. Often located under the steering wheel. They were first installed on Kia cars in 1996. In addition to the driver's, they are also installed for the front passenger, under the glove compartment.
Central defense
Since 2009, Toyota cars have had a central airbag. The main purpose is to reduce the secondary impact of passengers in side collisions. Often located in the armrest between the front row of seats. For the rear row of seats, it is located in the central part of the backrest.
In modern cars, except Toyota, the same ones are used in Mercedes-Benz cars (second generation Pre-Safe safety system). Thus, in the event of a side impact, this airbag softens the return impact of the passenger.
Pedestrian airbag
Since 2012, Volvo began introducing pedestrian airbags into its cars. Unlike all the above options, this type It is located outside the car, between the windshield and the hood. Thus, if a driver hits a pedestrian, the airbag will soften the blow and prevent serious injuries.
Mechanism design
The device looks like a soft shell and is filled with gas at the right moment; the set also includes a gas generator and a control system. The pillow itself is made of nylon fabric; in order to lubricate the pillow and not break during operation, talc or starch is used. They can often be seen in the air during airbag deployment.
The main purpose of the gas generator is to fill the pillow itself with gas. Thus, this is already an airbag module. Gas generators differ from each other in shape (tubular and round), in the nature of operation (with two-stage and single-stage operation) and in the method of gas formation (hybrid and solid fuel).
The most common is solid fuel; it consists of a housing, a squib and a certain charge. solid fuel. Typically, the fuel is ignited by a squib, resulting in nitrogen gas.
A hybrid gas generator consists of a squib, a gas charge under high pressure argon or compressed nitrogen, housing and solid fuel charge. The filling of the pillow itself occurs with compressed gas, as a result of pushing out a charge from solid fuel.
The airbag control system includes traditional shock sensors, a central control unit and an actuator (gas generator squib).
Operating principle
The main start for activation is a blow. Depending on which part and what strength of the blow, only the right pillows security. As soon as an impact occurs, the impact sensors are activated, then information about the force and location of the impact is transmitted to the central control unit. The unit processes the received data and determines the need to deploy specific airbags, as well as their time and strength.
In parallel with the airbags, information is transmitted to other sensors and systems, for example, an emergency braking system or an SOS signal. If the force of the impact is not significant, then only the seat belts can work, or they can also work in combination with airbags.
Paired with a signal on different systems, a signal is sent to the gas generator of the relevant airbags. On average, the response time of the airbags is about 40 ms. Thanks to the gas generator, the pillows are deployed and inflated. As soon as the pillow comes into contact with a person and has worked, it ruptures and deflates.
All cars always use disposable airbags. If a fire occurs in the cabin and the temperature reaches 150-200 °C, then the airbags are automatically deployed.
Conditions for triggering
The main conditions for the deployment of front airbags can be considered:
- exceeding the impact threshold (force) in a frontal collision;
- a sudden collision with a hard part at high speed (curb, sidewalk, pit wall, etc.);
- landing firmly after a car jump;
- car crash;
- an oblique or direct blow to the front of the car.
Video about how airbags work:
For many years, the tried and tested, good old belt was the only protector of passive safety in our cars. There has been much debate about the effectiveness of its use, especially for children, but over time, many countries around the world have made it mandatory to use seat belts in cars. Statistics have shown that the use of seat belts has saved thousands, hundreds of thousands of lives in the most serious accidents.
Just like with seat belts, the airbag concept, soft pillow into which you can “land” with your body during an accident has long been in the air, literally and figuratively. The first officially registered patent for an inflatable airbag (yes, they came to us from the skies) was issued during World War II. And only decades later the first airbags appeared on cars; this happened in the 1980s.
Since 1998, most new passenger cars(developed mechanical engineering) began to be equipped with airbags for both the driver and the front passenger. In 1999, this rule affected larger cars, jeeps and minivans. Then pillows began to appear in other places, in seats, doors and other parts of the car. Today, in some cars the number of airbags is much more than two; 6 and even 8 pieces have become the norm.
Having caused similar controversies as with seat belts, airbags have become the subject of serious research, testing and debate at the highest level.
Today, statistics confidently show that such devices reduce the risk of death by approximately 30%.
In this article you will learn about the operation of these devices, how their action is scientifically proven, what shortcomings they have and ways of future development.
Airbag
The purpose of an airbag is to slow down the forward motion of a person's body as evenly as possible in a fraction of a second. Here are three components of an airbag that help achieve this goal, that is, to operate at the right moment:
The pillow itself. Made of thin nylon, folded into the steering wheel, dashboard or seats, doors and other parts of the car.
Sensor. A device that “tells” the airbag to deploy. Triggering occurs when the impact force corresponds to a collision with a wall at a speed of 16-24 km/h. The signal for triggering the airbag squib is an electrical impulse from a special ball impact sensor. the impact goes to the control unit, which in turn determines whether the airbag inflation system is triggered or not.
Pillow inflation system combines two components, sodium azide (Nan3) with potassium nitrate (KNO3), to create nitrogen. He is the one who inflates the pillow.
Early attempts to adapt airbags for use in cars encountered a number of difficulties, some of which were incredibly high price and technical problems including storage and use of compressed gas.
In the early stages, researchers had to decide:
Where to place the compressed gas cylinder
Will gas stored under high pressure escape during the entire service life of the vehicle?
How to make a pillow unfold almost instantly, while being reliable under different conditions? temperature conditions operation and did not make a deafening sound when opened.
Gradually more and more important issues were resolved. The impractical gas was replaced by a reliable solid-state element - a squib, this happened in the 70s of the twentieth century. In the event of an accident, the “brains” of the airbags initiate ignition of the solid fuel charge, which burns at tremendous speed and creates a short time, 30-50 milliseconds, required quantity gas for filling the airbag. The pillow dome literally explodes as it emerges from its seat at speeds of up to 322 km/h, faster than you can blink an eye! A fraction of a second later, the gas under pressure comes out through special holes (it is this smoke in the car interior, mixed with talc, that can often be observed during an accident).
Types of airbags
Nowadays there are a large variety of airbags.
The most common type are front airbags, both for drivers and front passengers.
The next stage of development was side cushions. Their function is to protect the person’s chest and pelvis from damage during a side impact.
The so-called "curtains" or head airbags. Protect a person's head from contact with hard parts of the car during a side impact.
Knee airbag. To reduce the risk of injury knee joint(which often happens during a frontal impact), a similar airbag was developed.
Seat belt with built-in airbag. Reduces the risk of chest injury.
Central airbag. It was designed not so long ago. Its task is to prevent a collision between two people sitting next to each other during a side impact or rollover. It also avoids neck injury.
Security measures
From the very beginning of the use of airbags, specialists who studied the operation of this means of protection realized that it could bring not only benefits, but also harm. The second option is possible if the vehicle's passive safety equipment is used incorrectly. What does this mean?
1. Minimum distance There must be at least 25 cm between the airbag and the seated passenger, otherwise, when deployed, a person may be injured directly from the airbag itself.
2. The passenger must be wearing a seat belt. Since the seat belt reduces the speed of movement of the human body and directs it in the desired direction towards the airbag.
3. If an airbag can easily injure an adult, the situation is even more difficult with children. The first condition for the safe transportation of a child. He must be transported in a properly installed, age-appropriate seat in the back seat.
4. If a child must be transported in the front seat on the passenger side, then he must sit in a seat located in the direction of travel, and the seat must be moved as far back as possible.
5. Infants must not be transported in child seat with reversible position in the front seat with the front airbag on.
Hello, dear guests and blog readers Autoguide.ru. Today in the article we will learn how the airbags of our passenger cars. The crowning achievement of the evolution of car safety systems is the airbag. Hundreds of thousands of accidents and tens of thousands of lives saved are a clear example of the effectiveness of using airbags in modern cars.
Any driver who gets behind the wheel of a vehicle is automatically at risk of getting into a traffic accident. Often the cause of an accident can be one’s own carelessness or the mistakes of other participants. traffic. Even low speed is fraught with danger for the driver and his passengers. Car collisions at speeds of 60 km/h can be fatal. It is to protect the driver and passengers in the event of an accident that airbags were invented.
Increase in quantity road transport on the roads has led to a rapid increase in accidents. The rules at the dawn of the automobile industry were still in their infancy and control by law enforcement agencies was insufficiently established. The first traffic police units, which had no experience, were just emerging.
Due to design flaws and the significant weight of the vehicles, many accidents resulted in death or severe disability for those involved in the collision. According to statistics, the number of victims on the roads has increased every year due to the increasing use of road transport.
First structural elements The introduction of the seat belt was designed to reduce the number of road accident victims. Its use made it possible to reduce the sad statistics by 30%. Until the 90s of the last century, due to the peculiarities of technological progress, engineers of automobile companies were not able to introduce new safety systems into cars. The seat belt remained the only chance for the driver and passengers to minimize the harmful consequences of an accident.
The introduction of airbags in cars was a turning point in improving the safety of road users. At the end of the 90s of the last century in the United States, the mandatory equipment of cars with airbags was established at the legislative level. In frontal collisions, airbags reduce the risk of death of the driver and passengers by 30-40%. Main task Airbags minimize possible damage to the human body in the event of a collision with another moving vehicle or immovable object.
The airbag is designed in such a way as to ensure its deployment in the event of a strong impact. After a collision with another movable or immovable object, sensors located in the front of the car transmit a signal to the squib, which activates the airbag.
The order of airbag deployment is as follows:
Reaction of body sensors to a strong impact.
The shock sensor itself is a glass tube with a hole. Inside it is a small ball of mercury. When a car collides, the mercury ball moves and activates the sensor. He, in turn, sends an electrical impulse to the squib with gunpowder.
Squib.
The explosion of the squib activates the seat belt tensioners. The belt presses the person's body tightly against the car seat and securely fixes it for a few seconds.
The explosion of gunpowder in the squib activates the airbags. In a very short time they are filled with gas formed as a result of mixing sodium azide and potassium nitrate. The pressurization system is responsible for mixing them, which almost instantly pumps the resulting gas into the car’s airbags.
Airbag.
Mixing the two chemicals produces nitrogen gas. As a result of the reaction, a mini-explosion occurs, almost instantly filling the pillows with gas. A very convenient and practically trouble-free system.
It is the deployable airbag that instantly fills the space between the driver and the instrument panel, thereby eliminating their contact, which often leads to serious injuries.
The main task of the airbag is to reduce the speed of the passenger or driver to zero. At the same time, all actions should take seconds in order to truly ensure high level protecting people.
Today there are fewer and fewer cars on the country's roads that are not equipped with airbags. It's impossible to see a new car that doesn't use this important element active protection of the driver and passengers.
The design of a modern airbag
The airbag design of a modern car is simple and effective to use. It must be remembered that it can only be used once and then the system requires restoration and installation of new components. After the airbags are deployed, almost all the main elements require complete replacement.
In total, there are 3 components of the airbag:
Bag.
It is made of strong nylon fabric that can withstand very serious short-term loads. It is stored until triggered in a special tire covered with a plastic or fabric cover.
Shock sensor.
The main task of the impact sensor is to promptly activate the airbag at the initial stage of the collision. Not every impact triggers the airbags, and the sensor necessarily takes into account the force with which the collision occurs.
Additionally, accelerometers are installed with sensors that determine the position of the vehicle in real time. The driver and passenger protection system is configured to ensure that the airbags deploy within seconds. Human life largely depends on this.
Inflation system.
Serves to quickly fill the airbag with gas in order to instantly increase its volume. Everything takes a split second.
In principle, no cases of system failure have been recorded. A necessary condition Airbag deployment is achieved by using a seat belt. If the driver or passenger is not wearing seat belts, the airbags may not deploy.
Rules for using airbags
It is not enough to know the principle of operation of airbags; you also need to interact with them correctly in order to avoid harm from their deployment in an accident. The risk of injury when the airbag is activated is minimal, but it still exists. Often, individual drivers were seriously injured precisely because they did not know the rules for using airbags.
Child car seat.
Many parents often incorrectly install a child's car seat in the passenger seat next to the driver, thereby putting their child at serious risk. They install the chair not backwards, but vice versa. The child's face appears directly in front of the opening airbag. Doing this is strictly prohibited. A fired airbag can break the cervical vertebrae of a fragile young body.
Stickers.
The use of stickers in areas where airbags deploy is prohibited. Taping the firing elements of the interior can lead to a violation of the order of operation of the airbag. The effectiveness of protection in this case is significantly reduced.
Seat belt.
Airbag (airbag) is one of the passive safety elements in modern cars. Their presence is important factor ensuring the safety of the driver and passengers. Airbag translated from English language means " airbag", hence the Russian name - airbag, which we are all accustomed to using.
Airbags have saved thousands of lives since they were widely installed on vehicles. The idea behind the Airbag system is simple: airbags inflate quickly enough to protect the human body in the event of an accident. But how do they do it so quickly?
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Design and principle of operation of airbags
The secret of instantly filling airbags with air actually lies not so much in the airbags 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 an airbag about three times faster than you can blink. At the end of the article watch the video about how an airbag works and what stages of production it has to go through before being installed on a car.
The operating principle of airbags is quite simple. They are triggered upon impact when the vehicle speed exceeds 20 km/h.
- If the car collides with an obstacle, one or more special sensors are triggered. These sensors can be installed on the front, rear and sides of the vehicle.
- Signals from the sensors are processed by the electronic control unit (ECU), which controls the operation of the Airbag system. Under certain conditions (for example, a strong frontal or oblique impact, hitting 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 whether the airbags need to be deployed 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 activation of the squib, the sodium acid contained in the gas generator burns, releasing a significant amount of gas (nitrogen), which enters the Airbag and instantly opens it.
Airbags are made of nylon fabric similar to parachute fabric. It has holes through which gas, after inflating the pillow, leaves it in just 0.3 seconds. Rapid deflation is necessary because as air leaves the airbag, it becomes softer.
Each airbag has an inflator attached to it during the manufacturing process and is then rolled into a compact package (small enough to fit in the steering wheel or passenger side dash). In this case, the gas generator for the driver's airbag is additionally placed in a rubber ring, in which it acts as a balancing weight.
Airbag gas generator device
Since drivers and passengers are 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 vary their inflation rate relative to the size and position of the person, or the force of the vehicle's collision.
Therefore, the designers came up with a “smart” generator - it has two squibs instead of one. One of them releases gas at only 80 percent (this is enough for a “soft landing”). But if that's not enough, a second squib triggers a secondary fill and the remaining gas fills the Airbag and makes it stiffer.
A typical driver airbag inflator consists of the following main parts (see picture above):
- Housing with combustion chambers;
- Charges No. 1 and No. 2 from sodium acid tablets;
- Auxiliary charge for igniting charge No. 1;
- Two pyrotechnic cartridges for igniting charges;
- Metal filter.
So what happens in the gas generator when the Airbag is activated?
- The squibs installed in the airbag inflator contain a material similar to gunpowder. When they receive a signal from the electronic control unit, they are triggered, generating heat and high pressure.
- When a pyrotechnic cartridge is triggered, the special sodium acid tablets (charge) located there light up in the gas generator housing. These tablets release hot when burned, but safe gas based on nitrogen, which deforms the generator housing and leaves it, filling the Airbag.
- Before entering the airbag, the nitrogen passes through a special metal filter, which removes solid particles formed during the combustion of the charge and cools the gas.
- When electricity is supplied to squib #2, it ignites the second charge. The gas generated during the combustion of the charge lifts the cap of the stage No. 2 chamber and fills the airbag through the combustion chamber of the first stage.
From the moment the car gets into an accident until the airbag is completely inflated, no more than 30 milliseconds pass.
Types of car airbags
There are three main types of airbags that are most common in cars:
- Front airbags– 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 the event of an accident, they protect the human chest, abdominal cavity and pelvic bones. Such airbags are most often built into the backs of front car seats.
- Curtain pillows(head airbags) - designed to prevent head injuries due to side impacts. Automakers install these airbags in the roof area, both front and rear, or between the B-pillars.
Also on some car models you can find knee airbags and even a central airbag (between the driver and passenger). But these types of airbags are much less common. first three, and mainly on premium car brands.
Since airbags have become such an important component of the design of a modern car, engineers are constantly exploring the possibility of testing their functionality. German specialists, for example, developed and systematized a whole series tests taking into account climatic factors and vibration, extreme temperature changes and various conditions device triggering.
Manufacturers guarantee the flawless operation of airbags because, compared to the environment they create in 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 preceding 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.
