- Airbags, at what speed do they deploy?
Hi all! two weeks ago I was in an accident. Many people ask why the airbags didn’t work, saying they need to file a claim with the factory. Does anyone know at what speed the sensors are triggered, or even if someone is standing, the airbags can trigger? An old Mercedes drove into me (it flew past when the light was red), the impact was tangential from left to right when viewed from the driver’s seat. The front bumper was torn off, both side members and the radiator were crushed. Well, of course the wings and hood. I wonder, with such an impact the airbags should have deployed? How would I find out? Also, I was driving at a speed of no more than 15 km/h, and he was flying over 100. The whole thing happened at an intersection. I would appreciate any information! - Quote:
Posted by Hornist
Hi all! two weeks ago I was in an accident. Many people ask why the airbags didn’t work, saying they need to file a claim with the plant. Does anyone know at what speed the sensors are triggered, or even if someone is standing, the airbags can trigger? An old Mercedes drove into me (it flew past when the light was red), the impact was tangential from left to right when viewed from the driver’s seat. The front bumper was torn off, both side members and the radiator were crushed. Well, of course the wings and hood. I wonder, with such an impact the airbags should have deployed? How would I find out? Also, I was driving at a speed of no more than 15 km/h, and he was flying over 100. The whole thing happened at an intersection. I would appreciate any information!
If you had LTZ, the side ones might work
- Quote:
Posted by Hornist
Hi all! two weeks ago I was in an accident. Many people ask why the airbags didn’t work, saying they need to file a claim with the plant. Does anyone know at what speed the sensors are triggered, or even if someone is standing, the airbags can trigger? An old Mercedes drove into me (it flew past when the light was red), the impact was tangential from left to right when viewed from the driver’s seat. The front bumper was torn off, both side members and the radiator were crushed. Well, of course the wings and hood. I wonder, with such an impact the airbags should have deployed? How would I find out? Also, I was driving at a speed of no more than 15 km/h, and he was flying over 100. The whole thing happened at an intersection. I would appreciate any information!
This is a question for the dealer or GM hotline.
- with such a blow (tangentially) they should not work. speed is not important. can also work on a stationary car
- Quote:
Posted by Hornist
Hi all! two weeks ago I was in an accident. Many people ask why the airbags didn’t work, saying they need to file a claim with the plant. Does anyone know at what speed the sensors are triggered, or even if someone is standing, the airbags can trigger? An old Mercedes drove into me (it flew past when the light was red), the impact was tangential from left to right when viewed from the driver’s seat. The front bumper was torn off, both side members and the radiator were crushed. Well, of course the wings and hood. I wonder, with such an impact the airbags should have deployed? How would I find out? Also, I was driving at a speed of no more than 15 km/h, and he was flying over 100. The whole thing happened at an intersection. I would appreciate any information!
As a rule (on average for cars), the response threshold is from 30 km/h, I don’t know specifically for the Aveo, but somewhere like that.. That is. with your 15 they shouldn’t have worked anyway..
Quote:
can also work on a stationary car
No
- Santa, believe me, they can! and how!
- Do you think that if you are standing in a parking lot or at a traffic light, they turn off?
- Quote:
Message from Lex
Santa, believe me, they can! and how!
He meant that they can't work without a reason.
- Quote:
Posted by cancer32
He meant that they can't work without a reason.
What I meant was that if the system is working properly (the original sensors have not been replaced), then when standing up, even with any impact, the airbags will not shoot out, they need speed,
Usually it’s about (more than) 30 km/h, I don’t know exactly how much on ours..
Quote:
Do you think that if you are standing in a parking lot or at a traffic light, they turn off?
Naturally
Quote:
Santa, believe me, they can! and how!
Do not buy restored cars; as a rule (always) they are equipped with airbags that are not original, but ketai..
- The signal to activate the airbag squib is an electrical impulse from shock sensors (acceleration or pressure), arriving directly or through an electronic unit. Sensors are installed in the cabin, in the front of the car, or in the doors, and their number can range from three to ten. The response of airbag sensors is affected not only by the speed of the vehicle, but also by the nature of the collision (at what angle, with what obstacle). At the same time, emergency braking from any speed cannot trigger the shock sensor.
Under what conditions do airbags deploy?
In case of battery failure, some systems are equipped with a special capacitor, which releases the accumulated energy to open the airbags.
The driver's airbag has a volume of 60 to 80 liters, and the front passenger's - up to 130 liters. It is not difficult to imagine that when the system is activated, the volume of the cabin decreases by 200-250 liters within 0.04 seconds, which puts a considerable load on the eardrums. In addition, an airbag flying out at a speed of more than 300 km/h poses a considerable danger to people if they are not wearing a seat belt and nothing stops the inertial movement of the body towards the airbag
Airbag, operating principle
The main purpose of an airbag is to literally instantly and uniformly reduce the inertial forward speed of the driver.
It is made from thin nylon fabric. The airbag is located in the steering wheel and in the dashboard. In some cars, in the back of the front seat. There are also side airbags, it all depends on the model and make of the car.
The trigger signal is provided by a special sensor. The force at which the airbag deploys is equal to the force of a collision between a car traveling at 25 km/h and a wall.
The contact switch switches and the electrical contact closes.
The signal is sent to a sensor, which reads information from the accelerometer located in the chip.
When an airbag deploys, a chemical reaction occurs between potassium nitrate and potassium azide, producing nitrogen gas. The airbag is inflating.
This method of releasing nitrogen gas was developed quite a long time ago.
Since 1970, solid fuel gas generators have been used. The solid fuel is ignited by the squib and burns instantly, releasing nitrogen, which is enough to fill the cushion.
The pillow is filled with nitrogen at a speed of 300 km/h. The gas then begins to escape through a hole in the cushion to allow passengers to move. This is enough to protect and protect people in the cabin from serious injury.
There are certain rules on how to use airbags. They must be strictly adhered to.
Stability test
The purpose of the test is to determine how reliably the trunk and attachment with the installed load are fixed under prolonged exposure to forces in different directions (forward, backward, right, left). In real life, similar situations arise when you have to apply emergency braking or make a sharp turn to the side .
Video clip:
Test content
To test stability, stress is applied in different directions. The tension force is determined depending on the type of nozzle:
Tests are carried out according to the following standards:
- DIN 75302 and ISO 11154-4. In the project RMS test according to ISO 15263-4
- The time during which the maximum load is achieved is 5-10 seconds, unless otherwise specified. (According to DIN 75302 and ISO 11154-1)
Test equipment:
- The test platform is equipped according to the requirements of DIN 75302 and ISO 11154
- Maximum force: 20000N
- Maximum stroke length: 320 mm
- Measurement table: 0 ® 2000*2000 mm
- Data storage: Mecmesin AFI
- Force Measurement: External Mecmesin Load Cells
The voltage is tested using hydraulic equipment.
Airbag deactivation conditions
The National Highway Traffic Safety Administration has put forward a proposal to equip every car with an airbag. In 1984, the United States passed a law requiring all cars to be equipped with curtain airbags or automatic seat belts. However, as early as 1997, the National Highway Traffic Safety Administration issued regulations limiting the use of curtain airbags to prevent deaths or injuries due to high power emissions.
Image from murrayguari.com
This document regulates the placement of special devices in cars to protect children, pregnant women and people whose body proportions differ from the standard tested models. In this case, low kinetic energy airbags are installed. The deployment power of such pillows is approximately 25-30% less than conventional ones, but at the same time, the quality of their action does not decrease.
This is interesting
At the end of the 1990s, additions were made to the decree, according to which manufacturers were required to install special levers that disable the Airbag or slightly change their position.
It is possible to change the state of one or more airbags if the passenger or driver has certain contraindications.
The list of conditions under which the passive safety system can be turned off:
- If the driver or passenger has medical indications that pose a risk of harm to health from airbag ejection, and if this is more dangerous than failure, then it is possible to disable the mechanism.
- The driver's airbag is switched off if it is impossible to take a safe position while using the vehicle (the distance between the person and the passive safety system when closed must be at least 25 cm).
- The passenger airbag is disabled if car users carry a child in a child seat in the front seat, and the car does not have rear seats, or they are not suitable for installing and securing the seat.
There is another situation that allows the passenger airbag to be turned off - if the passenger is a child aged 1 to 12 years in the front seat under several conditions. The first condition is if frequent checks of the child’s health are required, the second is the absence of rear seats in the car, the third is insufficient space in the rear seats, resulting in the forced use of the front passenger seat.
Image from the website hyundai-club.kiev.ua
In any case, the activation of the driver's curtain airbags is mandatory if the distance between the torso and the steering wheel is 25 cm. If for some reason this position is not possible, the device should be turned off in order to prevent damage to health. The list of conditions under which the driver's airbag can be turned off: pregnancy, pacemaker, tonsillitis, recent spinal surgery, asthma, arthritis, osteoporosis, emphysema, advanced age of the driver or wearing glasses.
Urban Crash Test
The Urban Crash Test is performed according to the new Urban Crash Test standard proposed by the International Organization for Standardization (ISO). The test creates a situation similar to an accident in a traffic jam when the car speed is 18 km/h. Under these conditions, the weight of the bicycle is 20 kg , increases to 160kg (8g) at the moment of impact.
Video clip:
Carrying out the test:
- The product must remain in place.
- Deformations and slipping are resolved.
- Strength = 8g (on sled)
- Time = 50ms
- Speed = 16-0 / + 2kmh
- The test is carried out at room temperature, but most product protection functions are maintained at temperatures from -40°C to +60°C.
Airbag: types and how they work
Author Ksenia Belovetskaya
09.09.2019 13:40
Auto
Nowadays you rarely see a car without airbags. In any car there are at least two of them, in most cases there are about 6, in a premium car their number reaches 10. However, they can differ in both quality and function. Let's understand the types of airbags by reading the article below.
0 shared
Front airbag
The main type of airbag is the front airbag. It is installed in the front panel of the car and is designed to prevent injury to the driver and front seat passenger in the event of a head-on collision or other impact to the front of the car. The airbag sizes for the driver and front seat passenger are different because the driver's airbag deploys from the steering wheel and must fill a smaller space than the one deployed for the passenger.
Side cushions
This type of pillow is less common and is aimed at protecting the shoulders, abdomen, and pelvis. They are located in front and behind the passenger compartment and are activated during a side impact. They are usually inserted into the seats and upholstery of the car. Such airbags are not a popular safety feature and are usually not found in mid-range cars. In addition, their presence requires compliance with special rules: sharp or bulky objects cannot be placed in the seat pockets - they will prevent the airbags from deploying and can harm the person.
Ground movement test
A test to see product performance in real life situations. In order for the test to be considered successful, the rack, attachment and weight must remain in place during all tests and no deformation is allowed.
The test includes:
- Turns 50-70 km/hour, 3 repetitions
- Slalom 50-70 km/hour, 3 repetitions
- Braking 80 km/h, 3 repetitions
- Acceleration 190 km/h, 3 repetitions
- Driving over a speed bump
- (RMS products), 30 km/hour, 3 repetitions
Video clip:
Test equipment:
- A car on which a trunk and an attachment with an attached load are installed.
- Accelerometers for measuring the force acting on products at various stages of testing.
What types of airbags are there?
- Front airbags There are two front curtains in total - one protects the driver from injury, the other protects the passenger sitting in the front seat. The first is installed in the steering wheel, and the second is built into the front panel of the car. These airbags are designed to protect the head and neck from injury during an accident.
Image from sergievgrad.ru
- Front side airbags These are located in the front seat shells and serve to protect the torso and chest. If you have these types of cushions, it is important to choose the right seat covers because untested ones may prevent the mechanism from opening, which in the worst case could cause it to explode. On some models, airbags are built into the front doors and serve as protection in the event of a sharp impact to the side of the body.
- Knee airbags This type of airbag was developed by Kia; there are two of them - one protects the lower limbs of the driver, the other protects the leg of the passenger sitting in front from fractures and bruises. As a rule, such airbags are installed only on premium car models.
Image from autofixa.ru
- Head airbags In common parlance, these airbags are called “curtain” airbags. They are located on the inside directly under the roof of the car above the passenger seats. This type serves to protect the head and neck of passengers from injury.
- Seat belt with built-in airbag . Designed to prevent abdominal injury during a collision.
Regardless of the type of airbag, the main criterion for its successful operation is the quality of the material and originality (i.e. compatibility with the make and model of the car). In 80% of cases, cheap curtain airbags do not open fully or explode, causing even more damage to the people sitting inside the car.
Airbag
Tested with a fixed load. Once the 75,000 km threshold is passed, THULE conducts a further round of testing at a distance of 22,500 km to discover the weak points of the products.
Video clip:
The test was carried out using a special installation that simulates vibration and shocks while the vehicle is moving. Fasteners are always tested with a load installed on them. For example, bicycle racks are always tested with bicycles installed. Loading is carried out after installing the trunk and fastenings.
Test equipment:
- Trigger Unit: PLC
- Interface: RS232C
- Measurement table: 2200x1500 mm
- The test platform is built on three independently operating engines.
- The operation of any of the motors can be independently adjusted in terms of amplitude, speed and cycle time.
- The testing platform stands on a stand, which is a cube measuring 3x3x3 meters.
- Maximum amplitude of deflection of the nozzle with a load = 50mm
- Speed - 70-900 rpm.
- WEB camera.
Types of airbags
Let's look at the different types of these protective equipment in cars.
Frontal
From the name you can understand that this device is located at the front and is designed to protect people in the car. When the car hits an obstacle with its hood, a sensor is activated and the front airbags immediately pop up. They reduce the risk of impact, prevent fractures and serious injuries to internal organs.
They are located on the driver and passenger sides and have different sizes. The steering wheel with the airbag is located much closer than the panel from which the driver's side airbag emerges. It has a button that is used when a child is sitting in front.
In addition, you need to follow the rules, otherwise it will do harm. A person sitting in the passenger seat should not hold objects in their hands or rest their knees on the area where the device is located.
Steering wheel with deflated bag
Front side
They are not as popular as the previous ones and are mainly installed on expensive cars. The purpose of these airbags is simple: they protect the shoulders, sides and pelvic bones in the event of a side impact from a car. They are installed on both sides of the front seats. Side cushions also come with some safety precautions, such as avoiding keeping sharp, bulky objects in your pockets. When opened, they can harm a person.
Curtains
This type is designed to protect the head of the driver and passengers in the event of a side collision.
Curtain airbags can be of two types:
- for front seats;
- for front and rear seats.
Curtains are installed on the side of the car roof, above the windows and in the side pillars. They open so as to cover the side windows and prevent injuries from shrapnel and injuries from hard objects.
Knees
This type is designed to protect the legs and, in particular, the kneecaps when the car hood collides with an obstacle. It is located at the bottom of the dashboard under the steering wheel. If the knee cushion is deployed, it is necessary to calculate the adjustment of the driver's seat, because the legs must be at least 10 cm from the bottom of the dashboard.
Knee cushions in the cabin
Rear side
This type is designed for rear passengers and protects the shoulders, pelvic bones and sides. They are mainly located in the lower part of the side trim of the cabin. Such safety devices are not particularly popular and are produced in small quantities.
User test
Purpose of the test: to check how intensive use will affect the functions of the product.
Test content:
- Installing a bicycle rack on a car 50 times.
- Mounting the bike on the rack 200 times.
- Locking the bike with the key, installed on the mount, 1000 times.
Video clip:
Test equipment
The equipment used in this test differs depending on which THULE product is tested. For many tests, special mechanisms have been developed to ensure that the test results are as accurate as possible.
Airbag system design
Now let’s look at the design of this system itself. It consists of three components - a gas generator with a cushion (popularly called a “squib”), made in the form of one unit, shock sensors and a control unit.
The number of shock sensors, as well as the number of airbags themselves, can vary significantly. On some cars there can be up to ten such sensors installed throughout the car.
During a collision, this sensor transmits an impulse to the control unit, which in turn transmits a signal to the gas generator, which deploys the airbag.
Deployed airbags
The response of the sensor depends on several factors - car speed, angle of impact. The sharp drop in speed that occurs when a car collides with an obstacle ensures that the sensor transmits an impulse. But even emergency braking of the car is not able to activate the sensor.
From the signal received from the sensor, the control unit sends signals to the gas generators, while the unit “calculates” which airbag needs to be inflated, as well as how to inflate it. The fact is that some types of pillows have two circuits, the pumping of which is carried out depending on the force of the impact. In case of a weak impact, only one circuit is inflated, and if the collision is more serious, both circuits are inflated at the same time.
Test "environmental influence"
Purpose of the test: to evaluate how the functional characteristics of the product are maintained under unfavorable climatic conditions. All products are tested for the effects of temperature changes, ultraviolet radiation and susceptibility to corrosion.
Video clip:
Corrosion test:
- Aerosol spray of neutral solution (salt content according to ISO9227 and DIN50021).
- Aerosol spray of salt solution (salt: 5kg salt/100L aqueous, non-ionized water).
- Immersion of the product in the solution: 600-700 cm3/h. (water composition: 6-7 pH, deionized water).
- Water temperature: 45°C.
- Room temperature: 35°C.
Test results:
- There are no traces of white corrosion up to the 72nd sample.
- There are no traces of red corrosion up to the 240th test.
- Red corrosion on 0.05% of the surface after the 480th test.
Climate test:
- Humidity = 38°C/95%RF i 168h
- Climatic testing of the entire cycle is carried out according to P-VW 1200, 10 cycles = 120h
- Low temperature mode -40° C i 16h
- High temperature = 90° C i 16h
Effect of ultraviolet radiation (carried out according to ISO4892-2):
- The change in color of the product as a result of exposure to intense ultraviolet radiation is assessed.
- Temperature: +65°C.
- Water temperature: +20°C.
- Aquatic environment: 18 minutes.
- Air: 102 minutes.
- Test time: 1500 hours.
Smart airbags
Progress does not stand still, which is why engineers are striving to improve the passive safety system. At the moment, models are being tested that are capable of independently adjusting the volume of disclosure. It depends on the number of people sitting in the car. There are airbags that can independently calculate the optimal speed and force of operation, taking into account the temperature inside the car and the position of the seat belts. Many airbags are capable of independently monitoring their operating status, and if there is a risk of failure, a signal appears on a special sensor indicating a malfunction.
Packaging testing
The test consists of two different tests:
Transport test:
- It is carried out on a specially designed testing platform, simulating the conditions for transporting products in trucks.
- Oscillation amplitude = 2.5mm, 300 rpm och tid = 15h.
Falling from height
The drop height depends on the weight according to this table:
- 0.5kg – 9.5kg = 76 cm
- 9.5 kg - 18.6 kg = 61 cm
The test is considered successfully passed if:
- the product has no damage
- the packaging can still protect it from external influences.
Airbag operating principle
When the car collides with an obstacle, the sensors that control the curtain airbags are automatically activated. The presence of sensors and their location depend on the machine model. Typically, collision recorders are located near the driver and front passenger seats, near the doors and in the rear of the vehicle. Signs of a collision recorded by the sensor are intercepted by an automated system control unit. The block does not allow you to “throw away” the airbag if an emergency collision has not been identified (the exception is cases of hitting a curb or a direct impact on the windshield).
If the unit sends an electrical impulse to the system's gas generator, the squib fires. After the shot is fired, sodium acid burns inside the gas generator, and the nitrogen released during the combustion process is released by the Airbag. It opens in the event of an accident if the car was moving at a speed of over 20 km/h.
Airbags in a car
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 translated from English means “air cushion”, 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?
Why are airbags important?
One of the characteristic features that distinguishes our car owners from drivers in many other countries is the careless attitude of many of our compatriots towards traffic rules. Many people consider it shameful to use seat belts, and few people even think about such a thing as an airbag, let alone understand the mechanism of its operation. In fact, this invention helped save hundreds of thousands of lives and is today one of the most effective means of protecting the driver and passengers of a car.
Historical reference
From the very beginning, when cars appeared, no one really cared about safety equipment. And the speeds of the very first cars were modest, so everyone hoped that it would blow through. But as speeds increased, it became clear that it was impossible to do without means of passive protection for passengers. As a result, seat belts were invented. Despite all their shortcomings, seat belts turned out to be quite an effective tool that has served people for many decades and continues to serve people today. It was only at the end of the last century that airbags appeared.
At first they were installed only in the most expensive prestigious models, then they appeared in simpler cars, and then became a mandatory component of all passenger cars. For example, in the USA it is generally prohibited to produce and sell cars that do not have this protection. And there is a simple and understandable explanation for this strict rule - the presence of airbags increases the chance of surviving a head-on collision by 30%.
A little physics
Everyone knows what inertia is. All objects and passengers in a car have inertia. If an obstacle appears in the path of the car, it stops. And the passengers inside continue to move by inertia until they also encounter an obstacle. If a person is not secured in any way, then in the event of an accident he will definitely encounter an obstacle. This could be the steering wheel, dashboard, windshield, or something else.
The higher the speed, the more powerful the passenger's interaction with these hard and durable objects. A collision will not happen without serious consequences. The only thing that can save a person from injury is an airbag. In the event of sudden braking, it can reduce the inertial speed of the human body to zero, causing absolutely no harm to it.
How it works
In the event of a collision, the airbag deploys in a split second, creating a strong, but at the same time soft and elastic barrier between the instrument panel and the front passenger, between the driver and the steering wheel, between the rear passenger and the driver's seat. The inflation of the pillows is triggered by a command from a special sensor. It turns on and activates the protection system in cases where the force of the collision corresponds to a direct impact of the car against a wall at a speed of 25 km/h. This triggers a chemical reaction that instantly releases large amounts of nitrogen gas. With the help of this gas, safe for humans, the pillows are inflated. For them to be truly effective and help you and your loved ones avoid injury, you should follow a few simple and obvious rules:
- do not install the steering column in its highest position;
- do not store foreign objects in the place where the pillow is installed;
- do not allow physical impact on the places where the pillows are installed;
- Do not place a rear-facing child seat in the front seat.
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 a video about how an airbag works and what production stages 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.
How do airbags work?
For many years, a reliable seat belt remained the only form of passive safety in our cars. There have been debates about their safety, especially for children, but over time, most all countries have made it mandatory to wear seat belts on the road. Statistics show that wearing seat belts has saved thousands of lives that could have been lost in a collision.
But just like seat belts, the concept of airbags—a soft cushion to cushion a person from the effects of a crash—has been on the minds of engineers for years. The first patent for an inflatable emergency airbag for aircraft was filed during World War II. And in 1980, the first commercial airbag appeared in cars.
Today, the vast majority of low-cost passenger cars are equipped with airbags for at least the driver and front passenger. Statistics show that airbags reduce the risk of death in a direct frontal collision by about 30 percent. Increasingly, seats and/or doors are equipped with side airbags. Today, some cars go far beyond the current dual airbag standard, with six or even eight airbags for the driver and all passengers. But they are still the subject of considerable debate and research by government and industry.
In this article, we'll learn about the science behind these devices, how an airbag works, when it deploys, what its problems are, and how much technology has advanced today.
Laws of motion
Before looking at the specifics, let's review what we know about the laws of motion. First, we know that moving objects have momentum (mass times the object's speed). If some force acts on an object and then ceases to act, then the object will still continue to move, only reducing its speed - this is called inertia. A car is made up of several objects, including the vehicle itself, loose objects in the car, and, of course, the driver and passengers. If these objects are not attached to the car body, then they will continue to move at any speed the car is traveling at, even if the car is stopped by a collision.
Stopping the momentum of an object requires a force applied over a short period of time. In an accident, the force required to stop an object is very large, because the momentum of the car changes instantly, but the passengers do not, and there is not much time to work with. The purpose of any supplemental restraint system is to help stop the occupant while causing as little harm to him or her as possible.
The airbag is designed to slow the passenger's speed to zero with virtually no damage. At the same time, the framework within which it must work is enormous. When operating, the airbag occupies the entire space between the passenger and the steering wheel or dashboard in a fraction of a second.
The purpose of an airbag is to slow the occupant's forward motion as evenly as possible in a fraction of a second. The pillow consists of three parts, each of which helps to accomplish this feat:
- The bag itself consists of a thin nylon fabric that folds into the steering wheel or dashboard, or, in the case of a side cushion, into the door.
- The sensor is a device that tells the bag when to inflate. Inflation occurs during a collision with a force equal to at least a collision with a brick wall at a speed of 16-24 km per hour. The mechanical switch turns to close the electrical contact. The sensors, meanwhile, receive information from an accelerometer built into the microchip.
- The pressurization system is used to quickly pump gas into the cushion by reacting sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. A nitrogen explosion inflates the airbags almost instantly.
Early attempts to adapt the airbag for use in automobiles encountered prohibitive costs and technical obstacles associated with storing and releasing the compressed gas. The researchers asked:
- Where can I get the necessary sufficient space in my car for a gas cylinder?
- If the gas remains for a long time in its calm state under high pressure, then this is quite dangerous, isn’t it?
- How could the bag be expanded quickly and reliably at different operating temperatures and without a deafening explosion?
All questions of scientists disappeared when solid fuel came to the rescue in 1970. Solid fuel burns very quickly, creating a large volume of gas and making less noise.
Among other things, the air cushion is lubricated with powdery substances regularly—often cornstarch or talcum powder—to keep the bags flexible and lubricated while they are “in storage.”
At what speed do the airbags deploy?
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.
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 manufacturing 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.
Characteristics of airbags
Below we will talk in more detail about all the technical parameters and characteristics of this “inflatable” protection.
Purpose and functions
The main concern of an airbag in a car is to take care of the driver and passengers. It prevents vehicle occupants from colliding with the dashboard, windows, and other objects that could cause harm. If there is a belt and a cushion in the car, injuries will be minimized.
Usually it is located in the steering hub, and opens in 15-30 milliseconds, just at the time when the car has already collided with an obstacle, but the driver has not hit the steering wheel.
It consists of the following elements:
- inflatable bag made of dense elastic material;
- control lamp;
- a sensor that instantly responds when a car collides.
Mannequin driving a car
Operating principle
The device works like this:
- The car encounters an obstacle on its way.
- In the event of a collision, a sensor located in the airbag is activated. The entire system “wakes up” and begins action.
- A signal is sent from the system to the detonator and it provokes the filling of the “bag” with gas, which is under pressure. It instantly fills with gas and increases in size.
- In a split second it opens up, taking the blow. Having suppressed it, it deflates and falls off (author - Sergey Gromov).
Advantages and disadvantages
Pros:
- protects the chest and head;
- it is not an eyesore and is invisible in the cabin;
- you don't need to look after her.
Minuses:
- sometimes it can work by itself;
- makes a loud noise when filling;
- The driver's airbag does not operate if the car overturns or there is a side collision.
Deployed airbags inside a car
Airbag gas generator 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 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, when burned, release hot but harmless nitrogen-based gas, 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 by the combustion of the charge lifts the stage 2 chamber cap and fills the airbag through the first stage combustion chamber.
From the moment the car gets into an accident until the airbag is completely inflated, no more than 30 milliseconds pass.
What airbag gas is used today?
In modern conditions, nitrogen is used to fill the Airbag, which is produced when a tablet of sodium acid or sodium azide (NaN3) is burned. The system operation algorithm looks like this:
- When there is a strong impact in the car, sensors are triggered, the signal from which is sent to the gas generator.
- The gas generator begins to produce heat and high pressure, causing the cartridges to burn, producing gas.
- Since nitrogen in the total volume is only 45% (the rest is carbon oxide and dioxide, water vapor and solid particles), filters are installed at the gas generator outlet that do not allow components harmful to the human body to pass through.
- The pillow is filled in 20-50 ms. In this case, the pressure is maintained for no more than 1 s, after which nitrogen spreads through the technological holes into the car interior.
filling process
Nitrogen is an absolutely safe substance for humans. However, it is worth noting that in case of high concentration and pressure it can cause mild “intoxication”. Read more about this effect here.
The number of airbags in the cabin may vary. In the most secure vehicles, such elements are located not only on the steering wheel and front panel, but also along the entire internal perimeter of the car. Thus, during a serious accident, passengers find themselves inside a kind of capsule, which is designed to soften direct and lateral impacts.
Is there an alternative to NaN3?
In addition to sodium azide, some car manufacturers use nitrocellulose as a fuel to generate gas, which does not emit harmful substances during combustion and therefore does not require additional installation of a filter. In addition, with the same tablet weight, nitrocellulose produces more useful gaseous substances than sodium acid, which makes it possible to increase the power of the gas generator. At the same time, this substance is explosive, therefore, despite its obvious advantages, it is not widely used in the production of Airbags.
Thus, among the substances that release N, sodium azide currently has no viable alternative. But ready-made technical gases are not used because, firstly, it is not safe, and secondly, they require additional space to place the cylinder.
As a conclusion, we would like to draw your attention to the fact that airbags can protect you only if all necessary standards and requirements for their installation, replacement, production and use are met. However, in all sectors of activity it is necessary to comply with established rules.
Thus, she will be happy to professionally advise you on any issue regarding technical gases and gas equipment used in industrial and domestic applications - write questions in the comments. And if you need to purchase nitrogen, household, welding or food gas mixtures, then we are waiting for you on our website - there you can find complete technical information about the supplied products and be sure of full compliance with all necessary standards and rules.
Types of car airbags
There are three main types of airbags that are most common in cars:
- Frontal 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 the event of an accident, protect the person’s chest, abdomen and pelvic bones. Such airbags are most often built into the backs of front car seats.
- Curtain airbags (head airbags) are 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 than the 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, 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 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.
Airbag restoration
Owners of modern cars from time to time are faced with the need to restore airbags. Auto studio "Creative Studio Cars", among providing a variety of services for repairing, reupholstering and restoring cars, also offers high-quality services for restoring airbags in Tula.
Before turning to the services of the studio, the client needs to decide whether he needs to simply restore the airbag, repair the airbag, replace them, or completely restore the entire safety system of the car.
Car airbags are equipped with a disposable squib that cannot be restored. If you need working airbags, then replacement airbags are recommended. In this case, our studio offers the client to buy airbags and replace the old airbags with new ones.
Many motorists today are wondering how much it costs to change airbags ? The price of this service depends on whether you want to do just a cosmetic restoration of the airbag or completely change the airbags . When redecorating pillows, special “decoys” are installed instead of them. With their help, your on-board computer will not display a message on the instrument panel about problems in the SRS AIRBAG system. In this case, you will simply replace the pillows with “dummy” ones. The Creative Studio Cars auto studio offers replacement cushions made from materials as close as possible to the original ones. Highly qualified employees will restore not only the original shape of the airbags, but also the texture, color and even logos.
In our studio you can purchase Airbag airbags . Airbag installation is also our specialty. If necessary, we also perform a complete restoration of the entire electronic security system of the SRS Airbag.
Since replacing airbags is a labor-intensive and demanding process, our employees treat their work with special care. This provides clients with high results for the proposed work. The studio's services also include other restoration work on the car's interior, such as interior reupholstery, seat upholstery, steering wheel trim and much more. We carry out all work using professional equipment. By visiting the pages of our website, you can view a gallery with samples of certain works performed by our employees. By contacting our auto shop, you can be sure that the necessary work will be performed in a high-quality manner.
Video about how airbags work
Of course, not everyone will check whether a new car has an airbag.
The presence of airbags is written in the vehicle equipment document.
But if you bought a car that has already been driven before, you need to make sure whether they are real or not. The topic is becoming more relevant.
Naturally, if the person selling you the car has admitted to being in an accident in which the airbags deployed, you should ask whether they replaced them.
Airbag, first developments.
As is often the case, the road to developing an effective and reliable airbag was a tortuous one. And the first attempts to create them date back to 1941. True, this has not been documented, and development was suspended, wartime came and there was no time for that.
But then the war passed and the eyes of engineers again turned to the forgotten idea.
The invention is attributed to two engineers, who each created their own device, independently of each other, on different continents (this sometimes happens with outstanding inventions).
One of the creators was the German engineer Walter Linderer, the second was the American, John Hetrick. Thus, in 1953, a patent was first issued for a system capable of protecting a person from impact with hard objects in the cabin during an accident.
On August 18, 1953, a patent was issued to John Hetrick, and 3 months later, on November 12, 1953, another patent was registered for the invention of a German, Walter Linderer.
Is it possible to determine the presence of pillows?
Some car owners hide the fact that the airbags deployed and do not talk about the accident. What to do in this case?
Visually determine whether there are airbags, or using digital diagnostics . First of all, you need to determine where in the car they should be located. Next, you need to check if there are any scratches, defects or dents on the covers covering the pillow.
If deviations are noticed on the covers, most likely there are no pillows, or there are fake ones. The indication may indicate that the cushions are in place and functioning.
plugs can be installed in place of the airbags , simulating their presence for the monitoring system.
Without using the help of a car electronics specialist, you will not be able to know for sure whether there are airbags or decoys.
It happens that the car seller admits that the plugs are in place. In this case, you know for sure that you need to install real pillows to protect your life.
Problems of the first airbags
As it turned out later, the scientific research of a German engineer from Munich had one very significant flaw, which put an end to the development of a pillow using his technology. The German's airbag had a cylinder of compressed air, which filled the dome.
What was the mistake? The compressed air pressure was insufficient to rapidly deploy the airbag, causing the person to strike the steering wheel or dashboard before the airbag dome deployed. The idea had to be abandoned and the search began for new solutions and system components capable of filling the bag with gas in the shortest possible time. It was found in a squib capable of creating sufficient excess gas pressure in an extremely short period of time.
Around the same time, on the other side of the Atlantic, US Navy process engineer John Hetrick came up with a similar idea. The development of his airbag was helped by chance and official position.
As legend has it, Hetrick got the idea that it would be a good idea to keep occupants from coming into contact with the car's dashboard as a result of an accident while he was driving his car with his family. By a happy coincidence, no one was injured in that accident, not even the car was seriously damaged. But the experience so seriously affected the future inventor that upon arriving home, that same night he sat down to create drawings that were destined to become the prototype of the airbags of the future. Also useful in the development of the device was the experience of serving in the Navy, or rather the experience of servicing torpedoes.
Like the German, the idea was to use compressed air. The project was doomed.
Warranty period of pillows
If airbags are installed, it will not be superfluous to check the warranty period for which the car’s security system is activated.
Each vehicle has a different warranty period. Some cars have a connector for diagnostics and checking car systems. In addition to the connector, the car has a diagnostic device. If it is absent, the contacts in the connector will close at numbers thirteen and four.
The lights on the display panel will flash. If the security system is OK, the lights should flash every 0.5 seconds. The code indicating that there is a problem with the airbags will not be displayed.
If an airbag has helped a person at any time during an accident, the digital system contains an indication of the error.
To correct the indication that an error occurred, it is necessary to reflash the system.
But to do this, you need to find a professional, and this is a waste of time.
It is noteworthy that if you correctly flash the system, if you check the security system for the presence of airbags, the diagnostics will still give an error, or it may not.
Category Useful articles
Car airbags (common international name - airbag) are designed to soften the impact of the driver and passengers on the steering wheel, body elements and windows during a car accident. They are used in conjunction with seat belts. Airbags date back to the publication of Walter Linderer's patent in 1953.
Types of airbags
Modern passenger cars have several airbags, which are located in different places inside the car. Depending on their location, the following types of airbags are distinguished: frontal, side, head, knee, central airbag.
Frontal airbags first used on Mercedes-Benz cars in 1981. There is a frontal airbag for the driver and front passenger. The front passenger's front airbag can usually be switched off. Some front airbag designs use two-stage or even multi-stage deployment depending on the severity of the accident (the so-called adaptive airbags). The driver's front airbag is located in the steering wheel, the front passenger's - in the upper right part of the front panel.
Side airbags are designed to reduce the risk of injury to the pelvis, chest and abdomen during a crash. Volvo is a pioneer in the use of side airbags, which began offering them as an option in 1994. Side airbags are usually installed in the backrest of the front seat. A number of cars offer rear-seat side airbags. The most advanced side airbags have a dual-chamber design. It includes a harder lower part to protect the pelvis and a soft upper part to protect the chest.
Head airbags (also known as curtain airbags) serve, as the name suggests, to protect the head during a side impact collision. Toyota first began installing curtain airbags in 1998. Depending on the vehicle model, it is located in the front part of the roof, between the pillars and in the rear part of the roof.
The airbags protect passengers in the front and rear rows of seats.
A knee airbag protects the driver's knees and legs from injury. Located under the steering wheel. First used on Kia cars in 1996. Some models are equipped with a front passenger knee airbag, which is installed under the glove compartment.
In 2009, Toyota offered a center airbag , which is designed to reduce the severity of secondary occupant injuries in a side impact collision. Located in the armrest of the front row of seats, the central part of the back of the rear seat. Mercedes-Benz plans to use central airbags for the front and rear rows of seats in its second generation Pre-Safe system.
Currently, airbags extend beyond the passenger compartment. Volvo has offered pedestrian airbags on its cars since 2012.
Airbag device
The airbag consists of an elastic shell filled with gas, a gas generator and a control system.
The pillow itself is made of nylon fabric. To lubricate the airbag, talc or starch is used, which can be observed in the air in the cabin when the airbag deploys.
The gas generator is used to fill the cushion shell with gas. Together, the shell and gas generator form the airbag module. The designs of gas generators are distinguished by shape (dome-shaped and tubular), by the nature of operation (with single-stage and two-stage operation), and by the method of gas generation (solid fuel and hybrid).
A solid fuel gas generator consists of a housing, a squib and a solid fuel charge. The charge is a mixture of sodium azide, potassium nitrate and silicon dioxide. Ignition of the fuel occurs from the squib and is accompanied by the formation of nitrogen gas. A hybrid gas generator consists of a housing, a squib, a solid fuel charge and a high-pressure gas charge (compressed nitrogen or argon). The airbag is filled with compressed gas, which is released by a propellant charge from solid fuel.
The airbag control system combines traditional components - impact sensors, a control unit and an actuator (gas generator squib).
How airbags work
The airbags are activated upon impact. Depending on the direction of impact, only certain airbags are activated. If the impact force exceeds a preset level, the impact sensors transmit a signal to the control unit. After processing the data from all sensors, the control unit determines the need and timing of activation of airbags and other components of the passive safety system.
Depending on the type and severity of the accident, for example, only the seat belt tensioners or the seat belt tensioners together with the airbags may be deployed. The control unit supplies an electrical signal to activate the gas generators of the relevant airbags. The airbag deployment time is about 40 ms. The gas generator ensures the expansion and inflation of the pillow with gas. After contact with a person, the pillow ruptures and deflates.
Airbags are disposable devices. In the event of a car fire (the temperature in the cabin rises to 150-200°C), all airbags are automatically deployed.
Trigger conditions
The front airbags are deployed under the following conditions:
- exceeding the force of a frontal impact of a given value;
- hitting a hard, durable object (curb, sidewalk edge, pit wall);
- hard landing after a jump;
- car crash;
- oblique blow to the front of the car.
Front airbags do not deploy in the event of a rear impact, side impact, or rollover.
The condition for deployment of the side and head airbags is that the side impact force exceeds a specified value.
Algorithms for triggering airbags are constantly being improved and become more complex. Modern algorithms take into account the speed of the vehicle, the speed at which it decelerates, the weight of the passenger and his location, the use of a seat belt, and the presence of a child seat.
Related articles:
- HOW TO DRIVE IN WINTER Our climate is capricious. In the evening the weather is calm, and within an hour nature gives us a surprise...
- IMMOBILIZER The principle of operation of an immobilizerWhat is an immobilizer in a car and why is it neededImmobilizer - what is it...
- SEMI-INDEPENDENT SUSPENSION Technology has long ceased to stand still. Every year, new solutions are applied in the automotive world…
- NEW NIVA AUTO Back in 1970, three automobile plants were supplied with an important...
AIRBAG
Although the Airbag musicians list Pink Floyd, Radiohead, Talk Talk, Porcupine Tree and even A-Ha as their influences, it was the first group on the list that prompted them to embark on a creative path. This happened in 1994, when several schoolchildren from Oslo, who watched the concert of the British band (which visited Scandinavia as part of the Division Bell tour), were greatly impressed by what they saw and heard. For several years the guys divided their attention between studying and playing in the group, but already in 1999 they formed a stable line-up, which included Asle Tostrup (vocals), Bjorn Riis (guitar), Jorgen Hagen (keyboards), Andes Hovdan (bass ) and Juakim Slikker (drums).The following year, the team recorded the first sampler, but the official debut of “Airbag” took place in 2004 with the release of the EP “Come On In”. The minion was prepared for promotional purposes and, in addition to distributing the usual “hard copies,” it was posted freely on the Internet. The marketing move worked, and in a short time more than 10,000 people became acquainted with the work of the newly-minted ensemble.
Of course, critics immediately subjected the songs of the young Norwegians to a thorough examination, and one of the reviewers gave them a completely accurate description - “elegiac ambient prog.” With an interval of a couple of years, Airbag prepared a couple more mini-albums, “Sounds That I Hear” and “Safetree”, and all the songs were again posted online. When the number of downloads exceeded 230 thousand, the team was offered a contract from Karisma Records, and in August 2008 the musicians made a deal with this label. In April 2009, the company released the debut album on the domestic market, and a few months later the full-length became available outside Norway. “Identity” was made up of remakes from “Sounds That I Hear” and “Safetree”, and in the new edition the songs began to sparkle with bright colors and no longer seemed as monotonously soporific as the originals from minions.
In 2010, Airbag replaced the drummer with Henrik Fossum and, with his participation (as well as with the help of several guests), recorded the disc “All Rights Removed”. Here the group moved forward in a conceptual direction, heading towards long epic canvases and dramatic instrumentation.
The album included 6 thematic tracks, with the seventeen-minute “Homesick” becoming a concert favorite. Critics received "All Rights Removed" with even greater enthusiasm than "Identity", and the Norwegians' work topped various lists from the "Best Prog Release 2011" series six times. The quintet published their third studio album in the fall of 2013, with “The Greatest Show On Earth” presenting the dark side of the group, as the lyrics described the destructive forces of modern society. As for the music, it still combined the relaxed psychedelia of Pink Floyd and the indie sound of Porcupine Tree and Radiohead, but with all that, Airbag was developing its own style.
By the way, in addition to studio sessions, the team also worked successfully at concerts, and by that time they had accumulated many joint sets with such performers as “Anathema”, “Yes”, “Pineapple Thief”, “Riverside”, “RPWL” and “Gazpacho” " After hanging out at live venues for several years, the group returned in the summer of 2016 with the “Disconnected” program, dedicated to the alienation between the individual and society.
Last update 10/12/16
Airbag monitoring
Modern cars have up to 10 airbags, and this point is definitely worth paying attention to. It is better to check the presence of airbags and their functionality (if the restoration after an accident is of poor quality, there may be no airbags in the car at all) before you start using the vehicle. Otherwise, such connivance can be costly. If the airbags are faulty, a warning light should light up on the dashboard. This may indicate cable damage. For example, due to too fast and abrupt adjustment of the chair. It could also be a failed passenger presence sensor. If you do not find disconnected connectors in the cabin and do not find damaged sensors, you should connect the car to a diagnostic computer.
Airbags protect against many of the consequences of a collision. For example, from cuts from hard and sharp plastic elements of the interior that broke off during an accident. They also provide a body position that will reduce the likelihood of injury. The pillow itself can cause a little harm - cause a bruise or break your glasses. This is much less damage compared to what it protects from.
Device and principle of operation
Impact sensors are located in various places of the car - front, rear, sides - which are activated if the car collides with an obstacle at a speed of more than 20 km/h.
The electronic control unit, which controls the operation of the airbags, receives signals from the sensors and the unit gives a command to operate.
The signal is sent to the airbag gas generator, after which the squib charge is fired. As a result, the acid in the gas generator burns, releasing a certain amount of gas, which fills the bag, opening the airbag.
In order to soften the airbag itself, there are holes on its surface that provide a quick (less than a second after activation) release of gas from the airbag.
In modern cars, the Airbag generator is equipped with two squibs. The first is designed for relatively light collisions and releases approximately 80% of the gas. If this is not enough, the second cartridge fires. It releases the remaining gas, making the Airbag somewhat stiffer.
The pillows themselves are made from nylon-based fabric with the addition of starch or talc as a lubricant. The design of the pillows is provided in such a way that in standby mode they, in a compact, folded form, can easily fit in the steering wheel, on the front panel or in the sides of the seats.
Pedestrian airbags
Nowadays, engineers are developing passive safety systems for pedestrians. These curtain airbags are located on the outside of the car, near the windshield. According to statistics, about 85% of pedestrian deaths during accidents occur from hitting their head on the front of a car. The airbags located on the outside are deployed if special sensors detect an external impact. Some systems are equipped with Pedestrian Detection software and are linked to a computer that analyzes data about people in front of the car. During a collision, a mechanism is activated that opens the hood and ejects the Airbag to prevent possible injury to pedestrians.
This is interesting
Swiss engineers Anna Haupt and Teresa Alstin worked on creating special airbags for cyclists. This protection automatically activates in the event of a fall, protecting the head and neck from injury. This device has an opening speed of 0.1 seconds, thanks to which it functions like a high-quality helmet.
It is important to remember that the passive restraint system consists of a seat belt as well as an airbag, but if it is not fastened, the impact of the air curtain may be too strong and cause additional injuries. However, the presence of these elements in the car does not constitute permission for extreme and careless driving. Be careful and don’t take unnecessary risks, because the best safety system is your attentiveness and mutual respect on the roads.
Design and principle of operation of airbags (AirBag)
Airbags are a system that includes a gas generator with an airbag in one unit, impact sensors, and in the most modern ones an electronic control unit. The airbag itself is made of 0.45-0.55 mm thick nylon, which is covered with a layer of rubber or silicone for tightness.
A gas generator, often called a squib, uses solid fuel, the combustion of which releases gas that fills, or rather inflates, the cushion. The fuel is usually poisonous sodium azide (NaN3), 45% of the mass of which, when burned, turns into pure nitrogen, and the rest into carbon dioxide (CO2), carbon monoxide (CO), water (H2O) and particulate matter. Although the combustion process occurs quickly, it is not explosive. The optimal time for filling the pillow to ensure “inflation” is 30-55 milliseconds. Gas enters the pillow through a special filter that allows only nitrogen to pass through. The airbag remains in the deployed state for a very short time (up to 1 s), since nitrogen (absolutely safe for humans) quickly enters the passenger compartment through special openings so that the airbag does not suffocate the protected passenger. Some airbag manufacturers use nitrocellulose as fuel. To deploy an airbag, it requires significantly less (8 g) than sodium azide (50 g). This also does not require installing a filter.
The signal to activate the airbag squib is an electrical impulse from shock sensors (acceleration or pressure), arriving directly or through an electronic unit. Sensors are installed in the cabin, in the front of the car, or in the doors, and their number can range from three to ten. The response of airbag sensors is affected not only by the speed of the vehicle, but also by the nature of the collision (at what angle, with what obstacle). At the same time, emergency braking from any speed cannot trigger the shock sensor. In case of battery failure, some systems are equipped with a special capacitor, which releases the accumulated energy to open the airbags.
The driver's airbag has a volume of 60 to 80 liters, and the front passenger's - up to 130 liters. It is not difficult to imagine that when the system is activated, the volume of the cabin decreases by 200-250 liters within 0.04 seconds, which puts a considerable load on the eardrums. In addition, an airbag flying out at a speed of more than 300 km/h poses a considerable danger to people if they are not wearing a seat belt and nothing stops the inertial movement of the body towards the airbag.
In addition, filling the pillows in the cabin - and there are usually from 2 to 6 of them - is accompanied by increased noise, the level of which sometimes reaches 140 dB, which is dangerous for the eardrums. To avoid these “disadvantages”, only the necessary airbags are deployed, and then at different times: for example, 20 milliseconds after the collision - the driver’s, another 17 milliseconds - the passenger’s. Moreover, if there is no one to protect, the airbags do not deploy, since special sensors have begun to be installed in the seats that detect the presence of passengers.
Airbag and seat belt
Most drivers know that these two devices must be used in pairs. It is the belt that ensures the correct operation of the pillow. It prevents the body from leaving the desired position and takes the first impulse upon itself. The pillow, in fact, absorbs residual deformation.
If a person is not wearing a seatbelt at the time of an accident, the airbag will simply cause an additional blow to him. This can result in fractures and even death. This is why in many car models the airbags turn off if the belt is disconnected.
Main advantages of airbags
- Unlike seat belts, airbags do not require any action from the driver or passengers to activate. In the event of a dangerous situation, they are triggered automatically.
- The pillows do not restrict movement at all and do not cause a decrease in the level of comfort in the cabin. They are folded and invisible to the eye.
- The speed at which the airbag inflates is much faster than the occupants' normal reaction time in an accident. This leads to the fact that the protection of people inside the car is ensured regardless of the logic and sequence of their actions in a critical situation.
Airbag activation
For the airbag to operate, a signal from a complex control system is required. The device collects signals from sensors located throughout the car: accelerometers, pressure sensors, sound sensors and the brake system. It can detect the force of an impact and adjust the power with which the airbags deploy. The gas generator is activated. And the airbag is activated at a speed exceeding 300 km/h - filling it with gas (nitrogen or a mixture of helium and argon) occurs within 15-30 milliseconds. Modern sensors prevent the airbag from being activated during a minor collision.
Side curtains and knee pad
How do these extra pillows protect the body? A side curtain creates a barrier between a person's head and shoulder and the side window during an accident. Its function is to block contact with the body pillar, shards of broken glass and prevent falling out of the window. The knee airbag is designed to protect the driver from knee injuries that often occur in frontal collisions.
Side airbags
Although, from the driver's point of view, the difference between 30 and 10 milliseconds is not very noticeable, engineers had to take this into account when developing the side airbags. The doors are located closer to the human body than the steering wheel and front panel. Therefore, the airbags should deploy 20 milliseconds faster. To ensure such fast operation, highly compressed gas technology was used. It plays an important role in creating a “soft fit” for the hips and chest.
Seat adjustment
Many novice drivers sit as close to the steering wheel as possible. Perhaps they think that this way they can see the road better. In fact, in this position, the view, on the contrary, narrows. To get more space into your field of vision, you need to move back. Understanding this simple fact comes with time.
This situation is also dangerous because in the event of an accident the airbag will not have room to deploy. In this situation, she will not soften the blow, but, on the contrary, will deliver it, throwing the person back. Therefore, in order to avoid injuries, you cannot approach the steering wheel closer than 25 cm. If you lean against it, when the airbag is triggered, you can even die due to multiple fractures.
Actions with deployed airbags
To monitor the status of the operating airbag system, a monitoring program is used, which is a component of the vehicle’s on-board computer. When ignition occurs, a special light comes on and stays on for about 10 seconds; if it doesn’t light up, lights up constantly, or lights up on the road, this indicates problems in the mechanism. It is strictly forbidden to independently investigate the causes of an airbag malfunction; in this case, you should contact specialists who will conduct a detailed analysis of the system.
Image from sovet-kopilka.ru
Of course, you need to pay attention to the condition of the curtain airbags - regularly check the indicators on the sensor, and if they light up, immediately contact a car service center for repairs.
It is important
The airbag needs repair not only if it opens once, but also if the front panel of the car overheats.
For the correct functioning of airbags, it is not enough to replace used parts with new and certified ones; it is necessary to re-register the mechanism in the vehicle software, linking the new installation to the on-board computer.
