WORKING OF SAFETY AIR BAGS AND THEIR

MANUFACTURING

BY

THRIUMALA RAO

14745A0312

INTRODUCTION TO AIR BAG

An air bag is an inflatablecushion designed toprotect automobile occupants from serious injury in thecase of a collision.The air bag is also known asan air cushion restraintsystem (ACRS) or an airbag supplemental restraintsystem (SRS).This is because the air bag is designed to supplement the protection offered by seat belts.

AIR BAG SYSTEM

1. An air bag module

2. Crash sensors.

3. A diagnostic monitoring unit(ECU).

4. A steering wheel connecting coil.

5. Wiring and connectors.

AIR BAG SYSTEM WIRING DIAGRAM

HOW AIRBAGS WORK

1. The crash sensor senses the impact.

2. The diagnosis unit decides.

3. An electric signal is transmitted to the inflatorassembly.

4. The electrical signal then ignites the igniting agent.

5. The gas-generating agent ignites and generates gas.

6. "Airbags" inflate, while the "seatbelt pretensioner"simultaneously fastens the seat belt and absorbs theshock received by the passenger.

*Note: actions 1-6 above occur within 50 milliseconds.

AIR BAG DEPLOYMENT

• The airbag system ignites a solid propellant

(NaN3), which burns extreme rapidly to create

a large volume of Nitrogen gas to inflate the

bag. The bag then literally bursts from its

storage site and a second later, the gas quickly

dissipates through tiny holes in the bag, thus

deflating the bag.

THE MANUFACTURING OF AIR BAG

1. The propellant

2. The inflator assembly

3. The air bag

4. Final assembly of air bag module

5. Other components

RAW MATERIALS

Nylon thread A woven air bag Nylon fabric

Inflator canister And propellant

Applying silicone and urethane coating

I. The air bag:-a wovennylon fabric

II. Air bag coating:- siliconeand urethane

III. The inflator canister orbody:-stamped stainlesssteel or cast aluminum

IV. The propellant:-SodiumAzide (NaN3)combinedwith an oxidizer.

1.PROPELLANT

The propellant consists of sodiumazide mixed together with anoxidizer, a substance that helpsthe sodium azide to burn whenignited.From storage, the sodium azideand the oxidizer are then carefullyblended under sophisticatedcomputerized process control inisolated bunkers.After blending, the propellantmixture is sent to storage.Presses are then used tocompress the propellant mixtureinto disk or pellet form.

2. INFLATOR ASSEMBLY

The inflator components, such asthe metal canister, the filterassembly(stainless steel wiremesh with ceramic materialinside)and initiator (or igniter)are assembled on a highlyautomated production line toform inflator sub assembly .The inflator sub-assembly iscombined with the propellant toform the inflator assembly.The inflator assembly is thentested and sent to storage untilneeded.

3. AIR BAG

A die cut air bag fabric to the shape An inflated air bag for checking

The woven nylon air bag fabric is inspected for any materialdefects.The air bag fabric is then die cut to the proper shapes andsewn, internally and externally, to properly join the two sides.After the air bag is sewn, it is inflated and checked for anyseam imperfections

4. FINAL ASSEMBLY OF AIR BAG MODULE

The air bag is thenmounted to thetested inflatorassembly.

Next, the air bag isfolded, and thebreakaway plastichorn pad cover isinstalled.

Finally, thecompleted moduleassembly isinspected, tested andpackaged.

5. OTHER COMPONENTS The remaining components of the air bag system—the

crash sensors, the diagnostic monitoring unit, thesteering wheel connecting coil, and the indicator lamp—are combined with the air bag module during vehicleassembly.

All the components are connected and communicate through a wiring harness.

Connecting air bag module to vehicle

AIR BAG TESTING

This is a test rig which is set up in the laboratory.

DEPLOYMENT

This is a top view of the deployed driver and passenger airbag (Volvo)

CRASH TESTING

Front air bag crash testing Side air bag crash testing

The airbag systems are crash tested under varioustemperatures with and without loadings on the bag.The results of the test are then fed to the computers wherethe results are analysed

benefits

Airbags save lives.

They also reduce injuries.

By providing a carefully controlled gradient of deceleration, the human body comes through the crash relatively unharmed.

Conclusion

Airbags are an effective secondary safety measure that reduces the risk of injury for vehicle occupants, in more severe collisions. RoSPA supports the fitment of airbags in vehicles if they are used in conjunction with - but not in place of - seat belts.

conclusion

Air bags are of greater importance in today’s vehicles since safety of human life is of prior importance.

So far safe riding and for saving the precious life the safety bags must be implemented.

Let’s hope every automobile manufacturer implement the same.