air bag

CONTENTS

History of Airbag

Operation

Limitations

Airbag fatality statistics

Applications

Conclusion

Supplementary Restraint System for driver

and/or passenger safety in case of a crash.

HISTORY OF AIRBAG The airbag specified for automobile

use traces its origins as early as

1941

First invented by Walter Lind and

John W. Hetrick

At the beginning compressed air was

used

Types of Airbags

Frontal Airbags

Shaped airbag

Side Airbag

Side Torso Airbag

Curtain airbag

Knee Airbag

Rear Curtain Airbag

Centre Airbag

WORKING OF AIR BAG

Basic MechanismA thin nylon bag in the steering wheel /

above glove compartment inflates in the

event of an impact and prevents the

driver/passenger from hitting the steering

wheel/dashboard.

Main Components:

1) Airbag module

2) Diagnostic Unit

3) Crash sensors

Airbag ModuleContains both inflator unit and light-weight

fabric airbag and is located either inside:

1) Steering wheel hub

2) Above glove compartment

3) Near side compartment (as

separate/combined head/side/window-

curtain airbag)

Airbag: Thin nylon fabric bag folded neatly

into steering wheel that inflates to the size of

a large beach ball on impact.

Inflator unit:

Contains a number of sodium azide pellets

which are electrically ignited to produce N2

that then fills the airbag. This is preferred to

storing compressed gas in the unit (space,

durability)

Diagnostic Unit:Enables inflator unit and sensors when vehicle is turned on, performs self check.Constantly monitors airbag readiness and indicates malfunctioning through an indicator on dashboardUsually stores electricity to activate airbag in the event that a crash damages the battery / link to battery

Sensors:•Several crash sensors located in the front of

vehicle and in the passenger compartment.

•Each senses the sudden deceleration or

impact in the event of a crash and flips a

mechanical switch to indicate a crash.

Ball tube crash sensor

Airbag Deployment

Frontal crash scenario: Car crashes into an obstacle (wall) at 20+ mphSensors detect the deceleration and inflator unit activated

Deployment sensitivity: To guard against accidental inflation on hard braking, sensors detect collisions into a solid barrier at speeds greater than 8-14 mph only as impacts

An electric current is used to heat a filament wire that ignites the NaN3 capsules, producing N2:

2NaN3 2Na + 3N2

10Na + 2KNO3 K2O + 5Na2O+ N2

K2O + Na2O SiO2 alkaline glass (safe, unignitable)

Limitations ?

Airbag fatality statistics

Applications:

Airbag landing system

The Airbag Helmet

The unit is designed to shoot a protective,

inflatable nylon hood around the user’s head

within one tenth of a second of impact.

The Airbag Jacket

These jackets are designed to keep

motorcycle riders safe during a crash, and

typically have anchoring cables and a CO2

cartridge.

The Avalanche Airbag

The Cell Phone Airbag

• Honda teased tech aficionados with an idea of a

smartphone case that deploys an airbag when the phone

is accidently dropped.

• The case uses six small airbags placed around the

edges of the smartphone, which are deployed when the

case takes a spill.

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.