For years, the trusty seat belt provided the sole form of passive restraint in our cars. There were debates about their safety, especially relating to children, but over time, much of the country adopted mandatory seat-belt laws. Statistics have shown that the use of seatbelts has saved thousands of lives that might have been lost in collisions.
HOW ABOUT AN AIRBAGS?
Airbags are one of the safety features that can be incorporated in your car to protect you in the event of an accident. Airbags are known by many technical names, such as Supplementary Restraint System (SRS), Air Cushion Restraint System (ACRS), and Supplemental Inflatable Restraint (SIR).
The use of an airbag can protect your head, neck and chest areas. Airbags are fixed in by the vehicle manufacturers for the safety of the driver and passengers traveling in the vehicle. Normally, they emerge out of the steering wheel or from the dashboard, within a few milliseconds of the collision. When your head hits the airbag, the airbag starts deflating slowly, allowing you to get out of the car.
HOW DO AIRBAGS WORK?
1.The first stage of the airbag deployment is the accident itself. The collision, be it frontal or lateral, activates an array of sensors in the vehicle, including accelerometers, impact sensors, side pressure sensors, brake pressure sensors, gyroscopes and seat occupancy sensors.
2.All these sensors are in intimate connection with the ACU (Airbag Control Unit), the very brain of the airbag system. The unit decides if and how to deploy the airbags. When the ACU detects that the deployment threshold has been reached, it initiates the inflation stage.
3.As the compressed air system would have been impractical and quite inefficient, engineers came up with an idea quite similar to the working principle of the solid rocket booster. Each airbag incorporates a pyrotechnic device, known as an initiator or electric match, consisting of an electrical conductor cocooned in combustible material. A current pulse heats up the conductor, which in turn ignites the combustible material. This igniter triggers the chemical reaction that actually fills the nylon fabric airbag with nitrogen gas.The airbag’s inflation system reacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas.
4.The large volume of gas then forces the airbag out of the steering wheel and/or dashboard at a speed of up to 322 km/h, the whole process taking about 0.04 seconds. Considering that the blink of an eye is approximated at 0.2 seconds, one could say it’s quite a speedy process.
5.The last stage of the airbag process is the deflation, which occurs almost immediately after the inflation is completed. The gas escapes through special vents, which also prevent the occupants from suffering major impact injuries. Another effect of the deflation is the release of dust-like particles, mostly cornstarch and talcum powder, that are used to lubricate the airbag.
6.Initially, the chemicals used in airbags were a major health concern, but present systems will only produce a mild irritation of the throat and eyes.
7. So this is basic idea you need to know. I’ll post more about airbag, the consequence of airbag during the crash.