Safety and Feature of Auto-mobile

8/6/2019 Safety and Feature of Auto-mobile

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Guide By Prepared By

Prof. M.A.Patel Pithwa Alpesh.DProf. S.B.Jadeja Patel Samit.K

C.U.SHAH COLLEGE OF ENGG. & TECH.

WADHWAN CITY

Department of of Mechanical Engineering


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Acknowledgment

We gratefully acknowledgement the following reviews for their Insightful

Suggestion.

Prof. M.A.Patel (H.O.D. of Mechanical Department)

We are a ls o thank fu l to Prof . S.B.Jadeja (Prof . in Mechanical

Department) for guide us & providing components.

Finally we express out deep appreciat ion to our fr icnds who have

helped us Indirectly.

Pithwa Alpesh D.

Patel Samit K.


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AbstractM or e p eo pl e d ie o n r oa ds t ha n i n w ar . T he p ro te ct io n o f t he

automobile and the passengers is the most important task. Loss of croresof rupees is incurred as the automobiles are converted into pieces of junk.

We confront with one such news every day in our daily newspaper.

A trucker crushes a car at an intersection killing the driver instantly.

Reason: No cruise control or Maneuvering systems.

How can this be stopped ??

These acciden ts can be s topped by us ing appropr iate safe ty dev ices in

vehicles and by carrying our appropriate safety tes ts for vehicles . This p ap er d es cr ib es v ar io us s afety t es ts for automob iles and a ls o g iv es

overview of some commonly used safety devices.


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INDEXSr No. TOPIC NAME PAGE No.

1. Introduction 1

2. Safety testin g and i ts i mportan ce 2

2.1 Front Impact Test 2

2.2 Side Impact Test 3

2.3 Pole Test 3

3. Safety devices 4

4. Stability control system 5

5. Air bages 6

6. Safety seat belts 9

7. Collapsible steering wheel 10

8. Conclusion 11


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1. Introduction :

Every year millions of people die due to road accidents and traffic

mishaps . Dai ly we confron t one such news as ment ioned below in our

daily news paper

A Porchse 911, crashes into a farm equipment carrier.

No one survi ves.

Reason :

Non working Anti ock Breaking System (ABS).

A Grand Cherokee flies in air

Reason : Tire Burs t , The seat Belts breaks in to tow and the door of the

car pops out. A woman and a six-year-old boy are killed.

The q uest io n a ri ses i s How can thi s b e s to pp ed ? The ans wer to thi s

ques t ion may be yes we can avo id acciden ts bu t on ly i f we use p roper

safe ty devices . Today a wide varie ty o f safe ty tests are a lso avai lab le

which can reduce the percentage of accidents. A small care of using safety

device may save millions of life.

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2. Safety testing and its importance :

Passenger cars are des igned with a s tructure and features meant to

reduce the degree of in jury to passengers in the case of a coll is ion. The

method of test ing used to evaluate these features mus t ensure that theaccidents simulated ate as realistic as possible and that the data obtained

from the tests is highly reliable.

In this test, dummies are placed in both the drivers and front passengers

seats and the vehic le i s made to co ll ide wi th a concrete barr ier . The

d ummies a re check ed for injur ies to the h ead, n eck, chest and l eg s.

Following principle tests are popularly carried out for automobile safety.

2.1 Front Impact Test

Frontal impact takes place at 64kph (40mph), car strikes deformable

barrier that is offset.

In this test, dummies are placed in the drivers and front passengers seats

and the test vehicle is made to collide head-on on the drivers side (at an

offset of 40%) with an aluminum honeycomb. The dummies are checked

for in juries to the head, neck, ches t and legs , the vehicle is checked for

damage and deformation, and the results are used to evaluate the degree of

passenger protect ion in 5 levels . Actual coll is ions of th is type tend to

occur at speeds lower than that of th is tes t . Note that the results of th is

test do not apply to collisions at extremely high speeds, and other types of

col li sion s s uch as when p as seng ers a re n ot wearing s ea tb el ts , and

collisions in which one of the vehicles is a large truck.

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2.2 Side Impact Test

Impact takes place at 50kph (30mph). Trolley fitted with a deformable

front is towed into the drivers s ide of the car to s imulate a s ide-on

crash.

Among the passenger injuries

which occur in automobile

collisions, side collisions cause

the most damage next to frontal

collisions. In this test, a truck

with a weight of 950 kg is

made to collide at a speed of 55

km/h with the side of a

stationary test vehicle with a

dummy in the drivers seat orthe front passengers seats.

The dummy is checked for injuries to the head, chest, abdomen, and pelvis

and the results are used to evaluate the degree of passenger protection in 5

levels.

2.3 Pole Test

In Germany over half such injuries occur when a car hits a pole or a tree.

In the new test, the car tested is propelled sideways at 29kph(18mph) into

a r ig id pole. The pole is relatively narrow, so there is major penetration

into the side of the car.

In an imp ac t w itho ut

the he ad pr ote cti ng

airbag, a drivers head

could hi t the pole with

sufficient force to

cause a fatal head

injury.

Typically a head injury

c rit er ion of 5000 is

p os si bl e, f iv e t im es

t ha t w hi ch i nd ic at es

the likelihood of

serious brain injury. In

contras t , the head in jury cri ter ion in these new crash tes ts with a head

protect ion airbag is around 100 to300, well below the in jury reference

value. A side impact airbag with head protection makes this kind of crash

survivable despite the severity.

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3. Safety devices

ABS is an abbrevia tion fo r Anti - lock Brake Sys tem, and this device

maintains stability in the direction in which the vehicle is advancing and

enhances the possibility of avoiding an obstacle through wheel operation by preventing the tires from locking (ceasing to rotate) when emergency

braking is appl ied.

Inside ABS

There are four main components to an ABS system:

Speed sensors

Pump

Valves

Controller

Speed Sensors

The anti-lock braking system needs

some way of knowing when a wheel

i s a bout t o loc k up. The spe ed

sensors , which are located at each

whe el , or i n some ca se s i n the

differential, provide this

information.

Valves

There is valve in the brake line of each brake controlled by the ABS. On

some systems, the valve has three positions:

In position one, the valve is open; pressure from the master cylinder

is passed right through to the brake.

In position two, the valve blocks the line, isolating that brake from

the master cy linder . This p revents the p ressure f rom r ising fu rther

should the driver push the brake pedal harder.

In position three, the valve releases some of the pressure from the

brake.

Pump

Since the valve is able to release pressure from the

b ra ke s, t he re h as t o b e s om e w ay t o p ut t ha t

pressure back. That is what the pump does; when a

valve reduces the pressure in a l ine, the pump isthere to get the pressure back up.

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4. Stability control system

The operation and effects of the product:

Makes the vehicle stable when cornering when turning sharply to avoid anobs tacle o r a surface that i s unexpected ly s l ippery, the mot ion o f the

vehic le o f ten becomes uns tab le , fo r example skidding s ideways. This

system has an apparatus which control the motion of the vehicle in such

cases to makes i t more s table. If the vehicle begins to skid s ideways, a

sensor detects this and the brakes at each wheel are suitably controlled so

that the vehicle does not spin out or make a wide turn. The ability of the

s tabil i ty control sys tem to maintain s tabil i ty has l imit , and there s t i l l is

the dander that reckless driving will cause unforeseen accidents. Even if

the s tabil i ty control sys tem is ins tal led , always s tr ive according to road

condit ion , and when the warn ing l igh t i s operat ion p lease d r ive wi th

special care.

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5. Air Bags

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

in our cars . There were debates about their safety , especial ly relating to

children, but over time, much of the country adopted mandatory seat-beltlaws. 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. The attraction of a

soft pillow to land against in a crash must be very strong the first patent

on an inflatable crash-landing device for airplanes was filed during World

Wa r I I! I n t he 198 0s, the fi rst comme rc ia l a ir ba gs a ppe ar ed i n

automobiles.

Stat is t ics show that air bags reduce the r isk of dying in a d irect frontal

c ra sh b y a bo ut 30 percent. Newer than s teering-wheel-mounted or

dashboard-mounted bags , but not so widely used, are seat-mounted and

door-mounted side air bags.

The Basics

Before looking at specif ics , lets review our knowledge of the laws of

motion. First, we know that moving objects have momentum (the product

of the mass and the velocity of an object). Unless an outside force acts on

an o bjec t, t he o bjec t w il l con tinu e to mov e a t i ts p resent s peed and

direct ion. Cars consis t of several objects, including the vehicle i tself ,

loose objects in the car and, of course, passengers. If these objects are not

res tr ained, they wil l con tinu e mov in g a t wha tever s peed the car i s

traveling at, even if the car is s topped by a collision.

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Stopping an objects momentum requires force act ing over a period of

time. When a car crashes, the force required to stop an object is very great

because the cars momentum has changed instantly while the passengers

ha s not t her e is not muc h t ime to w or k wi th. The goa l of a ny

supplemental restraint system is to help stop the passenger while doing as

little damage to him or her as possible. What an air bag wants to do is tos lo w t he p as se ng er s s pe ed t o z er o w it h l it tl e o r n o d am ag e. T he

constraints that it has to work within are huge. The air bag has the space

between the passenger and the steering wheel or dash board and a fraction

of a second to work wi th . Even that t iny amount o f space and t ime is

valuable, however, if the system can slow the passenger evenly rather than

forcing an abrupt halt to his or her motion.

There are three parts to an air bag that help to accomplish this feat:

The bag i tself is made of a thin, nylon fabric, which is folded into the

steering wheel or dashboard or, more recently, the seat or door.

The sensor i s the d ev ice tha t t el ls the b ag to inf la te . Inf la tion

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 f l ipped when there is a mass shift that closes an electr ical

contact , tel l ing the sensors that a crash has occurred. The sensors

receive information from an accelerometer built into a microchip.

The a ir b ag s inflation system reacts sodium azide (NaN3) wi th

potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the

nitrogen inflate the air bag.

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The in fla tion sys tem is not unl ike a sol id rocket boos ter . The a i r bag

system ignites a solid propellant, which burns extremely rapidly to create

a large volume of gas to inflate the bag. The bag then literally bursts from

its s torage s i te at up to 200 mph (322kph) fas ter than the bl ink of an

eye ! A second later , the gas quickly diss ipates through t iny holes in the

bag, thus deflating the bag so you can move.

Even though the whole p rocess happens in only one-twenty-fifth of a

second, the additional time is enough to help prevent serious injury. Thepowdery substance re leased f rom the a i r bag , by the way, i s regu lar

cornstarch or talcum powder, which is used by the air bag manufacturers

to keep the bags pliable and lubricated while theyre in storage.

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6. Safety Seat Belts

A typical seatbelt consists of a lap belt, which rests over your pelvis , and

a shoulder belt which extends across your chest. The two belt sections are

tightly secured to the frame of the car in order to hold passengers in theirseats.

When the belt is worn correctly, it will apply most of the stopping force tothe rib cage and the pelvis , which are relatively sturdy parts of the body.

Since the belts extend across a wide section of your body, the force isnt

concentrated in a small area, so it cant do as much damage. Additionally,

the seatbelt webbing is made of more flexible material than the dashboard

or windshield. It s tretches a little bit, which means the stop isnt quite so

abrupt . The seatbelt shouldnt g ive more than a l i t t le , however, or you

might bang in to the s teering wheel or s ide window. Safe seatbelts wil l

only let you shift forward slightly.

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In a typical seatbelt system, the belt webbing is connected to a retractor

mechanism. The cent ral e lement in the re tracto r i s a spool , which is

attached to one end of the webbing. Inside the retractor, a spring applies a

rotation force, of torque, to the spool. This works to rotate the spool so it

winds up any loose webbing.

The central operating element in this mechanism is a weighted pendulum.

When the car comes to a sudden stop, the inertia causes the pendulum to

swing forward. The pawl on the other end of the pendulum catches hold of

a toothed ratchet gear attached to the spool. With the pawl gripping one

of i ts teeth , the gear cant ro tate counter-clockwise, and neither can the

connected spool. When the webbing loosens again after the crash, the gear

rotates clockwise and the pawl disengages.

The safety belt pretensioners are actuated by a gas generator triggered by

the a irbag con trol u ni t . The p re tens io ners h av e a lower d ep lo ymen t

threshold than the front airbags so that they may deploy in a collision thatis not enough to deploy t he front airbags . When ac tivated, the pretensi oner

tightens the webbing. Because the webbing is now tighter across the body,

occupants participate earlier in the vehicle ride down and loadings on the

body are distributed more uniformly over the entire restraint sequence, the

risk of injury declines.

7. Collapsible Steering Wheel

Earlier accident studies have shown that a rigid steering column represents

a special danger to the driver . Since the 1960s there have been various

designs to reduce the r isk of in jury. For example, s teering column and

steering wheel forwards, away from the driver. Since the introduction of

the airbag, the steering columns job has become more complex. It has to

supplement the p rotect ive potent ial o f the safe ty belt and the a i rbag.

Telescoping linkages and additional joints largely uncouple steering wheel

movement from bulkhead deformation. If the impact does not exceed a

certain severi ty, the s teering wheel and the airbag remain in a defined

posi t ion in front of the driver . An integrated s l id ing mechanism with a

damping function reduces the loads on the chest and head to the extent

technical ly feas ible. These elements are a good supplement to the beltforce limiters.

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8. CONCLUSION:

From above discuss ion the conclus ion that can be drawn upon is l i t t le

care to tie your seat belt or little cost to have airbags can save a valuable

life, so every individual should try to use this safety devices and every car

company should have their vehicles tested thoroughly for safety as safety

can save lives. We cannot give one so lets save life.

Safety Features of Modern Automobiles

Safety and Feature of Auto-mobile

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