Safety Air Bags in Cars

              

Air Bags have been under development for many years. The attraction of a soft pillow to land against in a crash must be very strong – the first patent on an inflatable crash-landing device for airplanes was filed during World War II. In the 1980’s the first commercial air bags appeared in automobiles.

                Since 1988, all new cars have been required to have air bags on both driver and passenger sides (Light Trucks came under the rule in 1999). To date, Statistics show that air bags reduce the risk of dying in a direct frontal crash by 30 percent. Newer than steering Wheel mounted or Dashboard-mounted bags, but not so widely used, are seat-mounted and door mounted side air-bags. Some experts say that within the nest few years, our cars would go from having dual air bags top having six or even eight air bags. Having evoked some of the controversy that surrounded seat-belt use in its early years, air bags are the subject of serious government and industry research and tests.

            

The Basics Of Air Bags : 

Before looking at specifics, let’s review our knowledge of the laws of the motion. First, we know that moving objects have momentum (the product of the mass and velocity of an object. Unless an outside force acts on an object, the object would continue to move its present speed and direction. Cars consist of several objects, including the vehicle itself, Loose objects in the car and, of course, passengers. If these objects are not restrained, they would continue moving at whatever speed the car was traveling at, even if the car was stopped by a collision.

Stopping an object’s momentum requires force acting over a period of time. When a car crashes, the force required to stop an object was very great because the car’s momentum had changed instantly while the passengers’ had not much time to work with. The goal of any supplemental restraint system was to help stop the passenger while doing as little damage to him or her as possible.
What an air bag wants to do was to slow the passengers’ speed to zero with little or no damage. The constraints that it had to work within are huge. The air bag had the space between the passenger and the steering wheel or dashboard and a fraction of a second to work with. Even that tiny amount of space and time was valuable, however, if the system could slow the passenger evenly rather than forcing an abrupt halt to his or her motion.

NEWTON,S SECOND LAW OF MOTION -BASICS OF AIRBAGS

• If objects aren’t restrained they would continue moving at the speed of the moving car even if the car was stopped by a collision.
• All airbags need to do was to slow down passengers speed.

MAIN PARTS OF AN AIR BAG

  1) BAG

              Was made up of a thin nylon fabric, which was folded into the steering wheel or dashboard or the seat or door.

             The powdery substance released ( regular cornstarch or talcum powder) was used to keep the bags lubricated while they’re in storage.

  2) SENSOR

             1) A device that tells the bag to inflate.   

             2) It works with the control module to discriminate between crash and non- crash  events.

 3) INFLATION SYSTEM 

                           NaN3+KNO3=large amts. of NITROGEN GAS.

                           Hot Blasts of the nitrogen inflate the air bag from its storage site up to 322Kmph.

WORKING OF AIRBAGS

         Air Bags are designed to inflate in frontal or frontal-angle impacts in which the car strikes an immovable object at more than about 16 Kilometers per hour or another car at twice that speed.  After a collision, sensors sense an electric current to an igniter system or, in some cases, to the computerized control unit.  This unit evaluates the situation and then sends an electrical impulse to the igniter system.  The electric current heats a filament (wire), which then ignites a capsule.  The Ignited capsule supplies the heat to ignite gas-generating pellets.  In most systems, the pellets are made of sodium azide and produce nitrogen gas when they burn.  In other systems, pressurized argon gas was used instead.  The gas then expands quickly and inflates the airbag, which then breaks through a plastic cover in the steering wheel or, the dashboard on the passenger side.  The whole process takes about 0.1 second from the exact moment the crash was detected.  The air bag starts to deflate immediately, venting the harmless gas through holes in the back of the bag of the through the fabric itself.

DISARMING THE AIRBAG

     Steps in disarming

•          Disconnect the battery
•        Wait 30 seconds.  The air Bag was equipped with a capacitor and it’s important to make sure that it was completely discharges before continuing.  Change the oil while waiting
•       Remove the airbag fuse.  The fuse Box was below the driver’s left knee; it folds down by squeezing on a couple of tabs near the top of the box.  Fuse also checks the diagram on the fuse box lid before pulling the wrong one.
•          Drop the sound insulator panel.  This was a plastic panel underneath the steering column.  It goes: steering column; interior colored panel; black colored panel.  The black panel was the one to remove.  There are two screws along the top and two finger-wing nuts along the back (one near the accelerator and one behind the emergency brake.)
•          Fastened to the sound insulator panel was a yellow circuit.  This was the airbag circuit.  To disconnect the circuit, you’ll first have to remove a green connector Positive Assurance lock which was for safety catch.  Both the green catch and the yellow connector are had to pull apart, but hey eventually would give.
•        Thus the bag was disarmed.  The only problems was, now the airbag light would be on all the time.  The airbag was fastened to the steering wheel with four Torx screws (T-30), accessible from the behind the wheel.  They won’t come all the way out they’re retained.  Once you have them all loose, the airbag would try to fall out.  The airbag was till connected by one or two wires.   The yellow one was the airbag circuit again; it was unplugged the same way as before, except this time the safety catch was blue.
•        Do not store it anyplace, which gets hotter than 130 degrees; do not heat it or apply electricity (even static).