29016637 Supercharger Ppt

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    By- Anshuman Panda

    B.E. (8th sem)


    Dayananda sagar college of engineeringB.E.(mechanical)

    Dated:25th march 2010

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    Supercharger , the engine booster.

    Why supercharger ??

    How it works ???

    Working diagram of supercharger.

    Classification of supercharger.

    History.Roots supercharger.

    Twin-Screw Supercharger.

    Centrifugal Supercharger.

    Drives used in Supercharger.

    Supercharger, An edge over turbocharger

    Nothing is perfect.


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    A supercharger is an equipment that compresses the air beingdelivered to an engine, allowing the combustion chamber to be

    overfilled without enlarging

    the space.

    The higher concentration of

    oxygen provided by a super-

    charger is matched with a larger

    amount of fuel from the fuel injectorsthus boosting the power of the


    A typical supercharger

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    Increases the power of an engine.

    A supercharger spinning at 50,000 RPM translates to a boost

    of about six to nine pounds per square inch(psi).

    Increases the torque produced.

    An efficiently working supercharger can achieve the same

    speed in one third time.

    Necessary in aero-planes as they have less oxygen at high


    Ensures complete combustion of the fuel.

    Reduces pollution to some extent.

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    More fuel + More air = Bigger explosion = Greater horsepower.


    But we cannot simply pump more fuel into the engine.

    The chemically correct mixture(14 : 1 :: air : fuel)is essential for anengine to operate perfectly.

    Thus superchargers provides more air by compressing air above

    atmospheric pressure , hence providing more fuel into the charge & would

    make for a more powerful explosion .

    Thus: Increased Power , Torque and Speed is achieved.

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    A standard engine with the addition of a supercharger

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    Based on method of compression, Superchargers can beclassified as:-

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

    volume of air per revolution at all speeds and a fairly constantlevel of boostregardless of engine speed.

    2. Dynamic compressors rely on accelerating the air to high

    speed and then exchanging that velocity for pressure bydiffusing or slowing it down & deliver increasing boostwith

    increasing engine speed.

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    The Roots supercharger is the oldest design of supercharger.

    Philander and Francis Roots patented the design in 1860 as a

    machine that would help ventilate mine shafts.

    In 1900, Gottleib Daimler for the first time included a Rootssupercharger in a car engine.

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    As the meshing lobes spin, air trapped in the pockets between the lobes

    is carried between the fill side and the discharge side & Large quantitiesof air move into the intake manifold and "stack up" to create positive


    Roots superchargers are usually large and sit on top of the engine.

    Roots superchargers are the least efficient supercharger for two


    1.)They add more weight to the vehicle.

    2.)They provide air in discrete bursts instead of

    providing in a smooth and continuous manner.

    Working of a roots supercharger

    Roots superchargerWorking:-

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    A twin-screw supercharger operates by pulling air through a pair

    of meshing lobes that resemble a set of worm gears.

    A twin-screw supercharger compresses the air inside the rotor

    housing (That's because the rotors have a conical taper, which

    means the air pockets decrease in size as air moves from the fill side

    to the discharge side).

    As the air pockets shrink,

    the air is squeezed into a smaller space.

    Working of a twin-screw supercharger

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    Thus twin-screw superchargers are more efficient compared to roots


    They cost more because the screw-type rotors require more precision in

    the manufacturing process.

    They also make a lot of noise.

    The compressed air exiting the discharge outlet creates a whine or

    whistle that must be checked with noise suppression techniques.

    Twin-screw supercharger


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    A centrifugal supercharger works by powering an impeller

    (a device similar to a rotor) at very high speeds to quickly draw

    air into a small compressor housing.

    Impeller speeds can reach 50,000 to 60,000 RPM.

    Centrifugal superchargers are

    the most efficient and the most

    common induction systems.

    They are small, lightweight and

    attachable to the front of the


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    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 air.

    Thus pressurized air is achieved.

    Working of a centrifugal supercharger

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    Belt (V belt, Toothed belt & Flat belt). Gear drive.

    Chain drive.

    Exhaust gas turbines:- Axial turbine.

    Radial turbine.

    Other:- Electric motor.

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    Superchargers do not suffer lag:- Superchargers have no lag

    time because they are driven directly by the crankshaft, whereasTurbochargers suffer from lag because it takes a few moments

    before the exhaust gases reach a velocity that is sufficient to

    drive the impeller/turbine.

    Modification of the exhaust system:- Installing a turbocharger

    requires extensive modification of the exhaust system, but

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

    that makes them cheaper to install and easier to service andmaintain.

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    Shutdown procedure:-No special shutdown procedure is required with superchargers as

    they are not lubricated by engine oil . They can be shut down

    normally. Turbochargers must idle for about 30 seconds or so

    prior to shutdown so the lubricating oil has a chance to cool down.

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    It derives power from the engine itself: Crankshaft drives

    superchargers so they steal some of the engine's horsepower. Asupercharger can consume as much as 20 percent of an engine's total

    power output.

    (But because a supercharger can generate as much as 46 percent

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

    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.

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

    maintenance add an extra burden on the expenses.

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    Despite their disadvantages, superchargers are still the most cost-

    effective way to increase horsepower.

    Superchargers can result in power increase of 50 to 100 percent,

    making them great for racing, towing heavy loads or just adding

    excitement to the typical driving experience.

    It is a must use component in an airplanes.

    With the use of high octane premium-grade gas , I think it is a

    miracle invention for speed junkies.

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