SAFETY AIRBAGS

IN CARS

SUMITTED TO: - SUBMITTED BY: -

Mr V.P. Singh Jitendra Kumar

Prof, Mechanical Engineering 1120382

M-3

SAFETY AIRBAGS IN CARS

INTRODUCTION

For years, the trusty seat belt provided the sole form of passive restraint

in our cars.

But over time, mush of the country adopted mandatory seat-belt laws.

Statistics have shown that the use of seat belts has saved thousands of

lives that might have been lost in collisions.

Air Bags have been under development for many years.

No safety device has consumed more attention and resources than the

airbag .

It is known with high confidence that when a crash occurs, the presence

of airbag reduces fatality risk to drivers.

Airbags are subject of serious government and industry research.

An airbag is a vehicle safety device .It is an occupant restraint system

consisting of a flexible fabric envelope or cushion designed to inflate

rapidly during an automobile Collision & restrain automobile drivers and

passengers in an accident, whether or not they were wearing their seat

Belts .

THE BASICS OF AIR BAGS

Newtons law of motion :

Newton's familiar first law of motion says that objects moving at a

constant velocity continue at the same velocity unless an external force

acts upon them.

If objects arent restrained, they will continue moving at the speed of

the moving car even if the car is stopped by collision.

All airbags need to do is to slow down passengers speed. Airbags

protect you by applying a restraining force to the body that is smaller

than the force the body would experience if it hit the dashboard or

steering wheel suddenly, and by spreading this force over a larger area.

Newton's third law ("For every action, there is an equal and opposite

reaction.") tells us that the body must exert a force on the steering

wheel that is equal, but opposite, to the force exerted by the steering

wheel on the body. Why, then, does the steering wheel not appear to

move when the body exerts this force on it?

DEVELOPMENT OF AIR BAGS

First patent on an inflatable crash-landing device for airplanes was filed

during World War II.

Allen Breed was holding the patent to the only crash sensing technology

available at the birth of the airbag industry . Breed invented a "sensor

and safety system" in 1968, the world's first electromechanical

automotive airbag system.

rudimental patents for airbags go back to the 1950s. Patent

applications were submitted by German Walter Linderer and American

John Hedrik as early as 1951.

Walter Linderer's airbag was based on a compressed air system .

John Hedrik received U.S. Patent in 1953 for what he called a "safety

cushion assembly for automotive vehicles .

Ever since 1988, it became a binding.

KEY DATES

1973 - The Oldsmobile Toronado became the first car with a passenger

airbag;

1974 - Buick, Cadillac and Oldsmobile offer dual airbags as an option on

several of their full-sized cars;

1980 -Mercedes-Benz introduced the airbag in Germany as an option on its

high end model W126 .

Mid-1980's - Ford and Chrysler introduce airbags in their vehicles;

1990 - Ford makes airbags standard equipment in its vehicles.

1990 - The first recorded accident between two vehicles in which an airbag

deploy to protect each driver occurs on March 12, 1990;

1995 - Volvo offers side airbags and torso side protection airbags as an

option on 850 models;

1998 - The federal government mandates duel frontal airbags on all

passenger Vehicles .

2006-Honda introduces first airbag systems for motorcycles American Honda

Motor, Corp.

MAIN PARTS OF AN AIRBAG

1.Bag

2.Sensor

3.Inflation system

HOW AN AIRBAG WORKS

air bags are designed to inflate in frontal impacts in which the car strikes

about 16 km/hr

The air bag system can be broken down into two main components.

These are the impact sensor and the air bag module unit. The impact

sensor does what its name implies, senses impacts.

The sensors are set to a sensitivity level where they will only deploy in an

accident .

The sensors function by detecting automobile deceleration.

When the automobile decelerates at a rapid rate, the sensors are

tripped.

This deceleration detecting is the job of two or more deceleration

sensors, placed at the front of the car.

When the sensors go off, they send an electrical current to the air bag

module unit, causing it to deploy.

Time taken for all these things about .1sec.

SENSOR

The sensor is the device that tells the bag to inflate.

It works with the control module to discriminate between crash and

non- crash events.

Several crash sensors located in the front of vehicle and in the passenger

compartment.

Ball tube crash sensor

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

The nitrogen gas is what causes the air bag to inflate.

This inflation occurs in an average of only 30 milliseconds.

When an occupant plunges into the air bag, the gas if forced backwards

through vents, a process which takes another forty-five milliseconds.

The whole sequence from initial detection of a crash, until the air bag is

fully deployed, happens very quickly

BAG is made of a thin, nylon fabric, which is folded into the steering

wheel or dashboard or, the seat or door.

The powdery substance released (regular cornstarch or talcum powder )

is used to keep the bags lubricated while theyre in storage.

INFLATOR ASSEMBLY

Control module activates the airbag assembly - an electric current is

sent to the detonator - ignition the sodium azide pallets evolves

nitrogen gas.

MODERN TYPES OF AIR BAGS

Curtain Air Bags

Developed by Mercedes and Volvo.

Inflate in front of windows to provide passengers better head and neck

protection.

More efficient at tipping and side impacts .

Future of airbags

Smart systems

Includes weight sensors

Determine type occupant in seat.ie.child or adult.

Infrared occupant

Detect the distance of passenger from airbags

LIMITATIONS

After airbags have been deployed, they may be difficult to re-position for

the next deployment .

The impact of an airbag can hurt a passenger who is improperly

positioned .

Deployment injuries can be most harmful to children and infants.

A vehicle must strike an inanimate object like a solid barrier between a

speed of 8 and 14 miles per hour for vehicle air bags to be deployed .

Harmful effects of sodium azide( during flatenning & recycling of

automobile)

CONCLUSIONS

Air bags are of greater importance in todays vehicles siince 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 implements the same

Reference

http://www.slideshare.net

http://www.seminarsonly.com

www.safercar.gov