working of safety airbags and their manufacturing
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Working of safety airbags and their manufacturingTRANSCRIPT
WORKING OF SAFETY AIR BAGS AND THEIR MANUFACTURING
By
Sandeep Kuriakose
Design and Manufacturing
Department of Mechanical Engineering
National Institute of Technology, Silchar.
Presented on:-08-09-13
An air bag is an inflatable cushion designed to from serious injury in the case of a collision. The air bag is part of an inflatable restraint system, also known as an air cushion restraint system (ACRS) or an air bag supplemental restraint system (SRS), because the air bag is designed to supplement the protection offered by seat belts.
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INTRODUCTION TO AIR BAG
An air bag is an inflatable cushion designed to protect automobile occupants from serious injury in the case of a collision.
The air bag is also known as an air cushion restraint system (ACRS) or an air bag supplemental restraint system (SRS).
This is because the air bag is designed to supplement the protection offered by seat belts.
A car air bag
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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 module
Steering wheel connecting coil
Crash sensor
Diagnostic monitoring unit
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AIR BAG SYSTEM WIRING DIAGRAMM
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HOW AIRBAGS WORK
1. The crash sensor senses the impact.
2. The diagnosis unit decides.
3. An electric signal is transmitted to the inflator assembly.
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 the shock received by the passenger.
*Note: actions 1-6 above occur within 50 milliseconds.
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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.
A front air bag deployed A side air bag deployed
Before deploymentAfter deployment
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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
An air bag manufacturing factory
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RAW MATERIALS
I. The air bag:-a woven nylon fabric
II. Air bag coating:- silicone and urethane
III. The inflator canister or body:-stamped stainless steel or cast aluminum
IV. The propellant:-Sodium Azide (NaN3)combined with an oxidizer.
Nylon thread A woven air bag Nylon fabric
Inflator canisterAnd propellant
Applying silicone and urethane coating
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1.PROPELLANT
The propellant consists of sodium azide mixed together with an oxidizer, a substance that helps the sodium azide to burn when ignited.
From storage, the sodium azide and the oxidizer are then carefully blended under sophisticated computerized process control in isolated bunkers.
After blending, the propellant mixture is sent to storage. Presses are then used to compress the propellant mixture into disk or pellet form.
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2. INFLATOR ASSEMBLY The inflator components, such as
the metal canister, the filter assembly(stainless steel wire mesh with ceramic material inside)and initiator (or igniter) are assembled on a highly automated production line to form inflator sub assembly .
The inflator sub-assembly is combined with the propellant to form the inflator assembly.
The inflator assembly is then tested and sent to storage until needed.
A cut section of inflator assembly
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3. AIR BAG
The woven nylon air bag fabric is inspected for any material defects.
The air bag fabric is then die cut to the proper shapes and sewn, internally and externally, to properly join the two sides.
After the air bag is sewn, it is inflated and checked for any seam imperfections.
A die cut air bag fabric to the shape
An inflated air bag for checking
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4. FINAL ASSEMBLY OF AIR BAG MODULE
The air bag is then mounted to the tested inflator assembly.
Next, the air bag is folded, and the breakaway plastic horn pad cover is installed.
Finally, the completed module assembly is inspected, tested and packaged. Assembly of an air bag module
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5. OTHER COMPONENTS The remaining components of the air bag system—the crash sensors, the
diagnostic monitoring unit, the steering wheel connecting coil, and the indicator lamp—are combined with the air bag module during vehicle assembly.
All the components are connected and communicate through a wiring harness.
Connecting air bag module to vehicle
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AIR BAG TESTING
This is a test rig which is set up in the laboratory.
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DEPLOYMENT
This is a top view of the deployed driver and passenger airbag (Volvo).
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CRASH TESTING
The airbag systems are crash tested under various temperatures with and without loadings on the bag. The results of the test are then fed to the computers where the results are analysed
Front air bag crash testing Side air bag crash testing
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REFERENCES
Crouse W. H. and Anglin D. L, Automotive Mechanics, Tata McGraw - Hill Education (2006).
Kirpal Singh, Automobile Engineering, Standard Publishers (2011).
http://www.madehow.com http://auto.howstuffworks.com
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QUESTIONS ???
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THANK YOU
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