INTRODUCTION

To Increase the output efficiency of any engine we have to burn more fuel and make bigger
explosion in every cycle. We have two options for this.

One way to add power is to build a bigger engine. But bigger Iengines, which weigh more and
cost more to build and maintain, are not always better.

Another way to add power Is to mice a normal-sized engine more efficient. We can accomplish
this by forcing more air Into the comubstion chamber.

More alr means more fuel can be added, and more fuel means a bigger explosion and greater
horsepower. This can be done with the help of a supercharger.

A supercharger is basically an air compress used for forced induction of an internal combustion
engine. It does the same work as that of a compressor, Le. It compress the air being delivered to
the combustion chamber of an engine. The greater mass ow-rate provides more oxygen to
support combustion than would be available In a naturally-aspirated engine, which allows more
fuel to be provided and more work to be done per cycle, increasing the power output of the
engine.

Thus a supercharger is extra equipment provided in an engine so as to boost the capacity and
the torque of an engine.

Why a supercharger

A supercharger is used In an engine for various reasons.

Some of the advantages of superchargers are as follows:

1- Increases the power of an engine.

2- A supercharger spinning at 50,000 RPM translates to a boost of about six to nine pounds per
square inch (psi).

3- Increases the torque produced.

4- An efficiently working engine with supercharger can achieve the same speed In one third of
the time taken by the same engine without supercharger.

5- Necessary in airplane and jets as they have less oxygen at high altitudes. So they provide the
sufficient amount of air by compressing it to higher prasure. And ensures complete combustion.
6- Higher amount of oxygen in compressed air from supercharger ensures complete combustion
of the fuel.

PRINCIPL of working
More fuel + More air = Bigger explosion = Greater horsepower.

Every supercharger works on the same above mentioned tagline.

It is quite evident that to get more output from any engine we need to burn more fuel. More
fuel will rault in a bigger explosion In every cycle, which will then push the piston with more
thrust, and consequently this thmst will be transmitted to the wheels with E OF WORKING the
help of crank and shaft. Wheels will rotate faster and with more power and that Is how it works.

But, to burn more fuel in an engine, we need more air in it

(The chemically correct mixture - ( - is

essential fer an engine to operate perfectly). Th us a

supercharger compresses the air being delivered to the

engine so as to supply mere air in the same, limited volume

of the cylinder. This ensures complete combustion of the fuel

and no unburnt fuel comes out of the exhaust. Thus the

supercharger inCreases the power output of any engine.

SUPERCHARGERS

Based on method of compression, Superchargers can be

classified as:-

l. Positive-displacement type, which deliver a nearly-fixed

volume of air per revolution at all speeds and a fairly constant

level of boost regardless of engine speed.

2. Dynamic compressors rely on accelerating the air to high

speed and then exchanging that velocity for pressu re by I

diffusing or slowing It down & deliver increasing boost with

increasing engine speed.

A supercharger comes In two dlerent variations:

Positive displacement and dynamic compressms.

A positive displacement supercharger pushes air into the

engine at a constant speed, while a dynamic supercharger uses

velocity to manipulate the pressure in the air.

In either case, oxygen is compressed as it is delivered to the

engine, allowing mOre power to be gained from every explosion

in the combustion chambers.

COMMONLY USED SUP GERS

Nowadays, there are several types of superchargers used in the

Following are some of the most commonly used superchargers

in the market.

5 The Roots supercharger is the oldest design of

supercharger used In any type of engine.

a Philander and Francis Roots, In 1060, Introduced the

concept of such type of equipment. Though they patented

the design as a machine that would help ventilate mine

shafts, later this turned out to be a miraculous invention

for automotive engineers.

2 In 1900, Gottleib Daimler for the rst time included a

Roots supercharger in a car engine which improved the

output of the engine. This was the rst step towards its

development.

ROOTS SU PERCHARGER

Constructional features: It consists of two meshing lobes that

are tted on two parallel shafts. Those lobes resembles to a lobe

gear that are In continuous mesh. Both the lobes mesh in such a
manner that the air pockets between these lobes and the side walls

goes on decreasing as air moves from the ll side to the discharge

side. Thus the passing air gets squeezed.

Working of Roots Supercharger: As the meshing lobes spin, air

trapped in the pockets between the lobes is rried between the ll

side and the discharge side a large quantities of air move into the I

intake manifold and 'stack up' to create positive pressure. This

pressurized air is received at the discharge side.

xv Roots superchargers are usually large and sit on top of the

engine.

r Roots superchargers are the least efficient supercharger for

two reasons:-

1. They add more weight to the vehicle.

2. They provide air in discrete bursts instead of

TWIN-SCREW SUPERCHARGERS

Construcuonel features: Twin-Screw Superchargers consist of

meshes in such a way that the air pockets between them goes on

decreasing as air moves ahead.

Working of Twin Screw Superchargers: A twin-screw

supercharger operates by pulling air through a pair of meshing

lobes that resemble a set of worm gears.

The rotors have a conical taper, which means the air pockets

decrease in size as air moves from the ll side to the discharge

side. Thus a twin-screw supercharger comprases the air inside the

rotor housing.

As the air pockets shrink, the air is squeezed into a smaller space. I

3' Thus twin-screw superchargers are more efcient compared

to roots supercharger.

> They cost more because the screw-type rotors require more

precision in the manufacturing process.

> They also make a lot of noise.

whine or whistle that must be checked with noise suppression

techniques.

CENTRIFUGAL SUPERCHARGERS

Construction-ml features: Centrifugal superchargers consist of an

Impeller with several blades that rotate at a very high speed at

around 50000 rpm. This impeller throws the air outside due to

centrifugal force. It also consists of a diffuser which exchanges the

speed for high pressure.

Working of Centrifugal Superchavger: As the air is drawn In the

hub of the impeller, centrifugal force causes it to radiate outward.

The air leaves the Impeller at high speed, but low pressure.

A diffuser converts the high-speed, low-pressure air to low-speed,

high-pressure alr.

Thus pressurized air is achieved. I

> Impeller speeds can read1 S0,000 to 60,000 RPM.

r Centrifugal superchargers are the most efcient and the most

common Induction systems.

engine.

r Thus the centrifugal superchargers are the best among the

above list.
DRIVES USED IN SUPERCHARGERS

Drives are basically the equipments that are used to transfer power

from one shaft to another shaft. In a supercharger, drives are used

to transfer part of engine power to the supercharger

There are several types of drives used to empower a supercharger.

These drives are used according to there requirements.

Some of them are as under:

> Belt (V belt, toothed belt & Flat belt).

> Gear drive.

i Chain drive.

Wines:-

r Axial turbine.

i Radial turbine.

m:-

> Electric motor.

In
SUPERCHARGER

AN

EDGE OVER TURBOCHARGER

Wm: - Superchargers have no lag

time because they are driven directly by the crankshaft, whereas

Turbochargers suffers lag because it takes a few moments before

the exhaud: gases reach a velocity that is sufcient to drive the

impeller/turbine.

Since the superchargers are directly empowered from the engine,

so as the engine starts, the superchargers can be activated. But in

the case of turbochargers they take some time for the accumulation

of exhaust gases.

W1 ' Instamg a turbOChal'Qel

requires extensive modification of the exhaust system, but

superchargers can be bolted to the top or side of the engine, that

malts them cheaper to Install and easier to service and maintain.

So this becomes a problem in the case of turbochargers. It

becomes a tough task to modify the exhaust system as well as it

adds an extra cost in the vehicle.

W: - No special shutdown procedure is

required with superchargers as they are not lubricated by engine

oil. They can be shut down normally. Whereas turbochargers must

oil has a chance to cool down.

Thus it creates a problem during shutdown procedure as

turbochargers cant be shutdown normally.

NOTHING IS PERFECT

> It derives power from the engine itself: Crankshaft drives

superchargers so they steal some of the engine's horsepower. A

supercharger can consume as much as 20 percent of an engine's

total power output. So it can be considered as a loss of engine

power.

(But because a supercharger can generate as much as 46

percent additional horsepower, I think the trade-off ls worth it).

Whereas this is not the case in turbochargers, it empowers Itself

from the exhaust gas of the engine, which is mainly a waste of

the engine.

a An added strain on the engine: Supercharging puts an

added strain on the engine, which needs to be strong to handle

the extra boost and bigger explosions. Engine and the other

connected medianisms have to be made robust enough to bear

the extra preure. So this makes the dsign engineer task

> An extra expense: Heavy-duty components, design complexity

& maintenance add an extra burden on the expenses. And these

expenss have to be made for better performance without any I

compromise.

Though this seems too much, but when compared to its output,

this seems a good deal.

CONCLUSION

r Despite their disadvantages, superchargers are still the

W to here! horsepower-

Superchargers can result in power increase of 50 to 100

percent, making them great alumina, Wham

loads or just W to the typical driving

experience.

"r It is a armament in an airplanes.

iv As superchargers Won. it greatly

mailman-MW

With the use WW I think it

is a miraclejnuentlnn for speed junklas.

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