Where are the side airbags located? The story of the airbag: toxic but irreplaceable. How many airbags are there in modern cars?
The most effective element of passive safety is the use of airbag systems. The airbag system, combined with diagonal lap inertia seat belts, in the event of a frontal collision provides additional protection for the head and chest of the driver and front seat passenger and reduces the likelihood of severe injury and death in accidents by 40%.
Rice. Airbag system (using the example of the Audi A3):
1 – impact sensor of the side airbag behind the driver (C-pillar); 2 – squib cartridge for charging the gas generator of the driver’s upper airbag; 3 – squib cartridge for charging the gas generator of the driver’s seat belt tensioner; 4 – switch in the driver’s seat belt buckle; 5 – driver side airbag gas generator charge squib; 6 – driver side airbag impact sensor (front door): 7 – driver airbag gas generator squib; 8 – diagnostic socket; 9 – instrument panel with warning lamps for seat belts and airbags; 10 – engine control unit; 11 – driver’s front airbag impact sensor (left front part of the body); 12 – front passenger front airbag impact sensor (right front part of the body); 13 – warning lamp for disabling the front passenger airbag; 14 – switch for disabling the front passenger airbag, operated by key; 15 – diagnostic interface of the data bus (gateway); 16 – squib cartridge of the first and second charges of the front passenger airbag gas generator; 17 – airbag control unit; 18 – switch in the front passenger seat belt buckle; 19 – sensor for the presence of a passenger in the front seat; 20 – squib cartridge for charging the gas generator of the front passenger side airbag; 21 – side airbag impact sensor on the front passenger side (front door); 22 – squib cartridge for charging the gas generator of the front passenger seat belt tensioner; 23 – squib cartridge for charging the gas generator of the front passenger's upper airbag; 24 – side airbag impact sensor behind the front passenger (C-pillar); 25 – central control unit for comfort systems; 26 – gas generator charge squib to disconnect the battery
Vehicles equipped with an airbag system for the driver and front seat passenger can be identified by a lettering on the soft panel of the steering wheel and on the right side of the instrument panel.
The main elements of the Airbag system are:
- set of inertial electromechanical and electronic sensors (3….5)
- gas generator squibs (energy source)
- airbags for driver (in the steering wheel) and passenger (on the right in the instrument panel)
- electronic monitoring and control device
- warning lamp on the dashboard
Sensors
Electromechanical shock sensors They work on the principle of a conventional limit switch - there is a metal ball in the tube, which, when struck sharply, overcomes the resistance of the springs and closes the contact, thereby forming an electrical circuit necessary for the operation of the system.
Currently, electronic sensors are used instead of mechanical ones. Such a sensor consists of a housing, a data processing unit and a micromechanical acceleration sensor, which can be piezoelectric, capacitor or other type.
A capacitor-type acceleration sensor is designed, to put it simply, like a capacitor. The individual plates of the capacitor are fixedly fixed. The elements associated with them are mobile and act as a seismic mass. During a collision, the seismic mass, in this case the moving plates, moves towards the stationary plates and the capacitance of such a capacitor changes. The data processing unit processes this information, converts it into digital form and transmits the data to the airbag control unit. 
Rice. Scheme of operation of a capacitor-type acceleration sensor:
1 – fixed plate; 2 – movable plate; 3 – data processing unit; a – state of rest; b - collision
Instead of acceleration sensors for collision detection, some car manufacturers install Pressure Sensors. With these sensors, faster detection of impacts in the door area is achieved.
Inertial sensors installed in the bumper, in the engine compartment, in pillars or in the armrest area. The sensors' memory contains parameters calculated in advance, which for a given car model mean exceeding the permissible impact. In the event of an accident, the sensors send a signal to the electronic control unit. In most modern systems, front sensors are designed for impact force at speeds of 25...50 km/h, while side sensors can be triggered by weaker impacts. From the electronic control unit, the signal is sent to the main module, which consists of a compactly laid pillow connected to a gas generator.
Gas generator squib
The melting wire or flame front within the ignition element (primer) energizes the airbag gas generators. In modern designs, the capsule for igniting the gas generator is triggered by alternating current in order to prevent the occurrence of a short circuit in the vehicle's electrical DC power system (malfunction in the electrical wiring). To create alternating current, a capacitor is incorporated into the charging capsule and connected in series to the drive circuit, which charges, discharges, or recharges at approximately 100 kHz.
The gas generator, often called a squib (tablet) with a diameter of 10 cm and a thickness of 1 cm, uses crystals of solid fuel, the combustion of which releases gas that fills, or rather, inflates the pillow. 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. An electrical impulse ignites the squib or melts the wire and the crystals turn into gas. The signal for triggering the squib is an electrical impulse from shock sensors (acceleration or pressure), arriving directly or through an electronic unit. Although the combustion process occurs quickly, it is not explosive. Combustion occurs in 3 stages: ignition, ignition for the fuse and combustion of the working charge. In a very short time the system develops power up to 60 kW, but no explosion occurs. Fuel combustion and inflation of the airbag with a volume of approximately 50...60 liters for the driver lasts 30...35 ms, the airbag for the passenger with a volume of approximately 100...140 liters is installed in the glove compartment area and inflates in approximately 50 ms. This time is less than the time it takes to blink an eye, which is 100 milliseconds.
To prevent injuries from inflating the driving pillow at a speed of 200...300 km/h towards the chest, modern pillows are inflated in two stages: first by about 70%, and when in contact with the body completely, two-stage gas generators are used for this.
Thanks to the radial straightening of the air bag and the sequential ignition of charges in such gas generators, the load that acts on the driver in an accident is significantly reduced. Depending on the severity and type of accident, the interval between the activation of both squibs can be approximately 5 ms. up to 50 ms. Both charges are always fired to eliminate cases when, after deployment of the airbag, there remains another squib that has not fired.
Airbags
In the event of an accident, the airbag control unit gives the command to ignite the first charge. The resulting pressure accelerates the piston, which opens the gas cylinder. The released gas fills and deploys the airbag. As a result of the combustion of the second charge, an additional amount of gas enters the air bag. 
Rice. Squibs with gas cylinder:
1 – first fuse; 2 – first charge; 3 – rod with piston; 4 – protective film; 5 – channels for supplying gas to the airbag; 6 – gas cylinder; 7 – second charge; 8 – second fuse
The inflation speed of the airbag is selected in accordance with the time the driver (passenger) moves when colliding with the airbag. Immediately after filling, but more slowly, the pillow deflates within 200 milliseconds.
The optimal time for filling the pillow is 30...55 milliseconds. Gas (nitrogen or other safe for humans) enters the pillow through a special filter. The airbag remains in the deployed state for a very short time (up to 1 s), since gas quickly escapes into the passenger compartment through special openings so that the airbag does not suffocate the protected passenger.
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 the 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 pillow is made of 0.45 mm thick nylon. For tightness, the inner side is covered with a very thin layer of synthetic rubber - neoprene or special silicone rubber. Modern pillows are divided into three types: front, side and ceiling.
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 reduce noise, 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 are no passengers in the cabin, the airbags do not deploy, since special sensors are installed in the seats that detect the presence of passengers.
Electronic monitoring and control device
Most current designs use an electronic unit that is installed in the passenger compartment to coordinate the operation of protection systems. The ECU's deceleration calculations are based on data from acceleration sensors used to monitor the deceleration forces that accompany a vehicle collision. The central electronic excitation unit must meet the requirements:
- identification of an accident or collision based on data received from an electronic acceleration sensor and a mechanical "safety detector" or from two electronic acceleration sensors ("full electronic recognition" control with redundancy circuitry)
- rapid response of control circuits, airbags and seat belt tensioners, based on special-purpose digital trigger algorithms, in response to various types of accidents (frontal collision, offset frontal collision, collision or collision at a certain angle, collision with a support, etc. .)
- stable voltage and power redundancy
- selective activation of the seat belt tensioner in accordance with the controlled state of the belt webbing - buckle assembly
- determining two response thresholds depending on whether the vehicle user actually uses a seat belt (high or low response threshold of the serial diagnostic interface)
Indicator light
A monitoring system can be used to monitor the health of the airbag system. When you turn on the ignition, the control light lights up for about 10 seconds, which should then go out. If the light does not light up, does not go out, or lights up while driving, this indicates a system malfunction.
Research by specialists shows that the risk of death of a pedestrian when hitting the hood of a car moving at a speed of only 40 km/h reaches 100%. To solve this problem, companies are actively working on developing airbags for pedestrians. This protection system includes two airbags - a large one that covers the front part of the car (bumper, radiator grille, headlights and hood edge) and a small one that is located near the windshield, protecting the pedestrian's head. Dangerous approaches to pedestrians and animals are detected by special sensors. These airbags will open immediately before a collision.
They appeared in production cars almost 40 years ago. During this time, pillows have saved and continue to save millions of human lives. Let's figure out what kind of airbags there are and how they protect the passengers of a modern car.
In fact, the patent for airbags was received already in the early 50s of the last century by the German inventor Walter Linderer. But airbags were installed on production cars only in 1980. Then the pioneer was the legendary Mercedes-Benz S-Class in the 126th body, which had an airbag for the driver mounted in the steering wheel. It is worth noting that along with the airbag, a system such as seat belt pretensioners also debuted. And the overall system, including airbags and pretensioners, is called SRS (Supplementary Restraint System or passive safety complex).
As for the airbag itself, it is a bag made of elastic nylon fabric, which in the event of an emergency is fired and inflated with a special gas (the squib ignites solid fuel in granules, which releases gas). A modern airbag fires in just 6 milliseconds - that's ten times faster than a person can blink.
Current car airbags are directly connected to all the sensors and electronic components of the car for a more accurate alignment of the so-called operation algorithms. This means that in a specific emergency situation (an impact of a certain magnitude, hitting an obstacle, landing after a fall, etc.), the airbag control unit takes into account the force and direction of the impact of the car with the obstacle, the speed of the car, the intensity of its deceleration, the exact amount passengers inside, as well as their height, weight and even the position in which they are sitting... Thus, the electronics determine which airbags need to be activated and, roughly speaking, how much to inflate them (modern airbags have a stepwise activation system In a modern car there may be more than ten different airbags located throughout the vehicle interior. Let's look at the main types separately.
Front airbags
Frontal airbags are located in the center of the steering wheel (driver's) and on the right side of the front panel (passenger). As we said earlier, modern designs of frontal airbags operate in a stepwise manner: in light collisions, the airbag inflates less strongly, minimizing the possibility of injury from an airbag shot, and in the event of a strong impact, it works at full force. Front airbags absorb approximately 90% of the total impact impulse, protecting the occupants' head and neck - the most vulnerable parts of the human body.
Side airbags
So-called side airbags appeared in production cars in the early 90s. These airbags can be built into both the front and rear seats. And in some convertibles, a similar pillow is even installed in the door panel. In the event of a side impact, the “cushion” expands, absorbs the inertia of the impact and protects the passenger’s pelvis, abdomen and chest from contact with the body.
Head airbags (curtain airbags)
“Curtains” can also be called side airbags, but they are only designed to protect the head and neck. Such “airbags” are built into the roof lining directly above the side windows and fire during a side impact, protecting front and rear passengers from the consequences of an accident. In addition, “curtains” can save you from cuts from broken glass and reduce the likelihood of serious injuries to the head and cervical spine when the car rolls over.
Knee airbags
As the name suggests, this type of airbag protects the lower limbs of the front passengers from contact with car parts. On the driver's side, such a pillow is located under the steering column, and on the passenger seat it “shoots” out of the cavity under the glove compartment. Knee airbags deploy in the event of a frontal collision, protecting the legs and knee joints.
Central airbag
The central airbag appeared in the 21st century. It is located in the center of the car and, depending on the design, can be located in the lower right part of the back of the driver's seat, in the front armrest or in the central part of the back of the rear sofa. During a side impact, the central airbag not only additionally holds passengers, but also serves as a kind of elastic partition that prevents them from hitting their heads. Also, according to test results, the central airbag additionally protects passengers when the car rolls over.
Airbag in seat belts
Yes, you heard right. There are even airbags built directly into the seat belt. In the event of a serious impact, the cylindrical bags in the shoulder straps of the rear passengers are inflated with a special cooled gas (the classic system is not used due to the release of a large amount of heat). These airbags help distribute the impact load evenly across the passengers' chest, reducing the risk of soft tissue damage.
Airbag in rear head restraints
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.
The content of the article:
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 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 of the cabin. 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 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 considered to be 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. Toyota was the first to use this technology 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 of the above options, this type is located outside the car, between the windshield and the hood. Thus, if a driver hits a pedestrian, the airbag softens the blow and prevents 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 considered to be solid fuel; it consists of a body, a squib and a certain charge of 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 of argon or compressed nitrogen, a housing and a charge of solid fuel. 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).
Principle of operation
The main start for activation is a blow. Depending on which part and the severity of the impact, only the necessary airbags are activated. 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 the signal to the various systems, a signal is sent to the gas generator of the corresponding 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:
The statistics of road accidents in our country sometimes resemble reports from the front - every day dozens of people suffer due to human negligence, adverse weather conditions and other factors. Automakers spend significant sums annually on ensuring vehicle safety, constantly introducing new developments and recalling entire batches due to certain problems.
An element of the safety system, such as an airbag, has proven its effectiveness and ability to mitigate the consequences of car accidents, but its use is associated with a number of nuances.
Airbag operating principle
The main task that airbags are designed to solve is to slow down the movement of the driver and passengers, preventing them from hitting the front panel, steering wheel or other parts of the car. Its design consists of the pillow itself, which is filled with gas, a filling system and a sensor.
In the event of a collision (although periodically the airbag may deploy when the wheel gets into a deep hole or hits an obstacle), the sensor gives a signal, after which potassium nitrate and sodium azide are mixed in the filling system, as a result, a gas is released, which fills the airbag.
The gas tends to dissipate quickly to allow the occupant to move. Modern cars contain diagnostic units that allow the airbag to operate even when the battery is not working, and also notify the driver of malfunctions in the system.
Despite their purpose of ensuring the safety of the driver and passengers, airbags can be a source of injury. Of course, it is not the pillow itself that is dangerous, but the fact that a number of rules are not followed when using it.
Let's start with the fact that the airbag deploys at high speed - up to 300 km/h. If you are not wearing a seat belt, you will simply collide with a fired airbag, which, given its speed, is fraught with at least a traumatic brain injury.
True, some manufacturers have provided the ability to deactivate the airbag if the seat belt is not fastened, but in both the first and second cases the risk of serious injury remains high. If the airbag deploys while your arms are crossed, in most cases fractures cannot be avoided.
There is a certain risk for those who use glasses: due to a strong impact, the glass may break or fall out, damaging the eyes.
If you are fastened, the belt slows down your movement and significantly reduces its amplitude, and the airbag itself softens the impact and minimizes the risk of injury.
It goes without saying that when driving at a speed of 140 km/h, in the event of a collision, even a combination of a belt and an airbag may not save you, because the car is tested at a speed of 60 km/h.
Where are the airbags located?
Finding where the airbags are located in a car is not difficult. To do this, just carefully examine the interior and find the inscriptions SRS Airbag or simply Airbag.
There are frontal, side, overhead (or curtain) airbags, and for the driver's knees. The driver's front airbag is located in the steering wheel; for the front passenger, the front airbag is located in the front panel above the glove box.
Side airbags are usually located in the seatbacks, in which case you will find either a badge or a plastic emblem with the corresponding message on the side of the seatback. Overhead airbags or side curtains are hidden either under the roof along the doors, or maybe in the side pillars. The driver's knee cushions should be found in the steering column area.
To prevent the airbag from becoming a source of additional injuries, you must follow a number of rules.
Firstly, always wear a seat belt - otherwise it will not only not save you from injuries, but may also become a source of new ones; The seat belt holds the body and prevents it from hitting.
Secondly, you need to maintain a distance between the front airbag and the chest - it should not be less than 25 cm.
Third, children should be transported only in a car seat that matches their build, height and age. The fact is that seat belts are designed for adults and cannot provide proper support.
Even in a low-speed collision, the cervical spine can be injured, and hitting the pillow will only aggravate this situation - the risk of injury if you ignore the car seat increases five times. Ignoring safety standards when it comes to children is doubly unacceptable.
As you can see, the airbag is a recognized protector that can reduce the risk of injury by 25-30%, but only if all safety requirements are met. Ignoring the belt or a malfunction of the system can cause serious injuries, so do not give up an extra way to protect yourself and your loved ones.
An airbag in a car, wherever it is located and of whatever type, is installed to protect passengers and the driver from impacts that they may receive inside the car as a result of a collision. Such a device often saves lives and protects against injury in emergency situations.
To provide better protection, airbags are combined with seat belts. Belts can be used without pillows, but pillows cannot be used without a belt. Because if a person is not secured with a seat belt during an accident, the airbag will not help him. In this case, he can harm himself and others. If a person is not fastened, then in a collision the airbag will only injure him. He is also at risk of head and neck injuries.
Types of airbags: what they consist of
The airbag is an elastic shell that, if necessary, is filled with gas using a gas generator. Pillows are usually made from nylon fabric. They are usually triggered when the car hits or collides with something. When a car collides, sensors installed in the car determine the force of the impact and determine which airbags should deploy. After this, the sensors send a signal to the control unit. The airbag then opens inside the cabin at just the right moment to protect the person.
Types of airbags: what is the difference
The name of the airbag depends on where it is located. There are different types of pillows:
- Frontal
- Lateral
- Head ones
- Knees
- And also central.
Popular types of airbags
Frontal
This is one of the most common cushions most often used when equipping cars. First of all, it protects the driver and the person sitting in front from hitting the front parts of the car inside the cabin, and also softens the impact. Thus, the pillow protects the human internal organs from damage. The airbag for the driver is located in the center of the steering wheel, and for the front passenger - on the front panel of the car.
These two front airbags differ in size. Smaller for the driver's seat than for the person sitting in front. This airbag is activated if a frontal collision occurs. The airbag can be disabled, but only for the front seat. Depending on the severity of the accident, two-stage or multi-stage operation occurs.
Lateral
A less common type of pillow. They are usually equipped with expensive cars. They are designed to prevent a person from damaging the pelvis, abdominal cavity and chest, and are triggered if a side collision of the car occurs. Such pillows are divided into types: curtain pillows that protect the entire interior of the car, or pillows that protect a person.
Side airbags can be located:
- in the back of the front seat
- in the car door
- in the back seats.
These pillows have a two-chamber design, which consists of an upper part (it is soft) and a lower part (it is hard). The upper part of the pillow protects the chest from injury, and the lower part protects the pelvis.
Less common types of airbags
Head ones
The main function is to protect the head in the event of a side collision with a car. Such airbags are used to protect everyone who is inside the car, regardless of where the person is sitting: in front or behind. The pillows are located between the pillars in the roof, in the rear and front of the car.
Knees
Protects knees and shins from damage in the event of an accident. These airbags are located under the steering wheel and under the glove compartment (for the front passenger).
Central
This new species appeared not so long ago. The airbags inflate during a side impact and help avoid secondary collisions for passengers. For people sitting in front, such a pillow is placed in the armrest of the driver's seat. And for people sitting behind them - in the center of the rear seat.
Airbags are intended for single use. If opened, they must be replaced. You can buy and install new airbags by contacting specialists. Only those that have worked will need to be replaced.
