The document provides a comprehensive overview of airbags, detailing their history, components, and functioning. It explains the mechanics of airbag deployment during collisions, highlights advantages such as improved occupant safety, and acknowledges disadvantages including potential harm to individuals too close to deploying airbags. Future advancements in airbag technology, including hybrid inflators and smart sensors for occupant detection, are also discussed.

1. Topic: AIRBAG
Mechanical Engineering

2. AIRBAG

3. Overview Of the TOPIC
 Introduction.
 Development of Airbag.
(History)
 What does it Consist of ???
(Main Parts)
 Airbag Module.
 Crash Sensor.
 Propellant.
 Working of Airbag.
 Summary.
 Advantages.
 Disadvantage.
 Head and Chest protection.
 Future aspect.
 Query.

4. Introduction
 An airbag is a vehicle
safety device. It is a type of
restraint system that
consists of a flexible fabric
bag, also known as an airbag
cushion. The airbag module is
designed to inflate rapidly
then quickly deflate during
a collision or impact with
another object or a sudden
deceleration. The purpose of
the airbag is to provide
occupant protection and
restraint during a crash
event.

5. Development of Airbag (History)
 The air bag traces (air filled bladder) - as early as 1941 and first
patented in the 1950s.
 Early air bag systems were large and bulky, primarily using
tanks of compressed or heated air, compressed nitrogen gas
(N 2 ), Freon, or carbon dioxide (CO 2 ). Some of the early
systems created hazardous byproducts. One particular
system used gun-powder to heat up Freon gas, producing
PHOSGENE GAS (COCl 2 )—an extremely poisonous gas.
 One of the first patents for automobile air bags was awarded to
industrial engineer John Hetrick on August 18, 1953.
 In 1968, John Pietz, a chemist for Talley Defense Systems,
pioneered a solid propellant using sodium azide (NaN 3 )
and a metallic oxide. This was the first nitrogen-
generating solid propellant, and it soon replaced the older,
bulkier systems.

6. What does it consist of ??
(Main Parts)
 An air bag system consists of an air bag module, crash sensors, a
diagnostic monitoring unit, a steering wheel connecting coil, and
an indicator lamp.
 An air bag module has three main parts:
 the air bag,
 the inflator, and
 the propellant.
 The driver's-side air bag material is -- heat shield coating
to protect the fabric from scorching, especially near the
inflator assembly, during deployment. Talcum powder or corn
starch is also used to coat the air bag; either substance prevents
the fabric from sticking together and makes it easier to assemble.
 The propellant, in the form of black pellets, is primarily sodium
azide combined with an oxidizer and is typically located inside
the inflator canister between the filter assembly and the initiator.

7. Airbag Module
 Airbag:-It is sewn from a
woven nylon fabric. which is
folded into the steering
wheel or dashboard or, the
seat or door.
 The Inflator Assembly:-
NaN3 + KNO3 = produce
large volume of nitrogen gas.
 Nitrogen Gas inflate the air
bag from its storage site up
to 322Kmph. Control
module activates the airbag
assembly - an electric
current is sent to the
detonator - ignition the
sodium azide pallets –
evolves nitrogen gas.

8. Crash Sensor
 The sensor is the device
that tells the bag to inflate.
 Inflation happens when
there is a collision force
equal to running into a brick
wall at 10 to 15 miles per
hour (16 to 24 km per hour).
A mechanical switch is
flipped when there is a mass
shift that closes an electrical
contact, telling the sensors
that a crash has occurred.
 The sensors receive
information from an
accelerometer built into a
microchip.

9. Propellant
 The propellant (sodium azide)
mixed with an oxidizer (Metallic
Oxide), it helps the sodium azide
to burn when ignited. Different
manufacturers use different
oxidizers.
 The sodium azide and the
oxidizer are carefully blended
under sophisticated
computerized process control.
Due the possibility of explosions.
 This all components of the air
bag system—the crash sensors,
the diagnostic monitoring unit,
the steering wheel connecting
coil, and the indicator lamp—are
connected through a wiring
harness.

10. Working Of Airbag
 In a frontal collision equivalent
to hitting a solid barrier at nine
miles per hour (14.48 kilometers
per hour), the crash sensors
located in the front of the car
detect the sudden deceleration
and send an electrical signal
activating an initiator
(sometimes called an igniter or
squib). Like a light bulb, an
initiator contains a thin wire that
heats up and penetrates the
propellant chamber. This causes
the propellant,
principally SODIUM AZIDE, -
to undergo a rapid chemical
reaction (a pyrotechnic chain).

11. Working Of Airbag
 Thus harmless N2 gas so produced
fills the air bag.
 The gas inflates the nylon bag in
less than one-twentieth (1/20) of a
second, by opening its plastic
module cover and - in front of the
occupant.
 As the occupant contacts the bag,
the N2 gas is vented through
openings in the back of the bag.
The bag is fully inflated for only
(1/10th ) of a second and is nearly
deflated by (3/10th) of a second
after impact. Talcum powder or
corn starch is used to line the
inside of the air bag and is released
from the air bag as it is opened.

12. Summary

13. Advantages
 Inflate in front of windows to
provide passengers better head
and neck protection.
 More efficient at tipping and
side impacts .
 Reduce HIC (Head Injury
Criterion) by 80%.
 Frontal air bags have saved
25,782 lives between 1987
and 2008. However, they
are supplemental safety
devices. Always wear your
seat belt.
 The first use of airbags for
landing were Luna 9
and Luna 13, which landed on
the Moon in 1966 and returned
panoramic images.
http://www.iihs.org/iihs/ratings/safety-
features - which car include which type of air bag.
HONDA-Accord,Civic.
TOYOTA-Camry,Corolla.
BMW-X1,3,4,5,7 Z4
AUDI-A-3,4,5,6,8,R8

14. Disadvantage
 Recent News 8th Oct, 2015:-A three-month-old
baby travelling in his mother’s arms as she drove to
the shop died after an airbag deployed following a
collision. (Dublin, Ireland)
 The force of an airbag can hurt those who are too
close to it.
 The one factor that is common to all who died
is NOT their height, weight, sex, or age.
Rather, it is the fact that they were too close
to the air bags when they started to deploy.

15. HEAD and CHEST protection
 Side-impact air bags
(SABs) offer protection to
two principal areas of the
body -- the head and the
chest .
 SABs providing Chest
protection (or "torso"
bags).
 SABs providing Head
protection (or “Curtain"
bags).
 SABs providing both
protection (or “combo"
bags).

16. Future Aspect
 A hybrid inflator is currently
being tested that uses a
combination of pressurized inert
gas (Argon (Ar)) and heat from a
propellant to significantly expand
the gas's volume. It would have a
cost advantage- less propellant
could be used.
 Systems that would eliminate the
sodium azide propellant, which is
toxic in its undeployed form.
 "SMART SENSORS” to check
the deployment of the air bag to
certain conditions. These
sensors- sense the size and
weight of the occupant, whether
the occupant is present.
 SMART (SENSORS) SYSTEMS
 Weight Sensors:
 determine what type of occupant is
in the seat, i.e. adult or child.
 Infrared Occupant detection:
 To detect the distance the
passenger is from the airbag .
 Capacitive Reflective Occupant
Sensing:
 Identify the distance passengers
from the dashboard.
 To discriminate between a human
occupant and inanimate objects