Sunday 1 May 2016

Superchargers

What are Superchargers?

Supercharger is a device used for forceful air induction inside the combustion chamber. Since the development of internal combustion engines, engineers have been looking for ways to increase the power output of an engine without adding much weight to the engine. Superchargers in a way prove to be one of the major breakthroughs in achieving so.

Superchargers force more air to be supplied to the combustion chamber during the intake stroke in order to allow the fuel injection system to inject more fuel. In other words, superchargers send more oxygen to the combustion chamber to form an oxygen rich air-fuel mixture. Oxygen rich air-fuel mixture will result in greater horsepower and also higher torque during the power stroke. A normal engine if supercharged would produce 40% to 50% more horsepower and 30% more torque.

What is the difference between a supercharger and a turbocharger?

As we are aware that turbochargers also help in forced induction of air to the combustion chamber, the difference between turbocharger and supercharger is the power source from which it gets its drive. Turbocharger is run by the exhaust gas flow, whereas supercharger is run via a belt drive from engine.

Types of Superchargers:

There are 3 types of superchargers:

·         Centrifugal supercharger
·         Roots Supercharger
·         Twin Screw Supercharger

All the 3 superchargers are driven by the engine crankshaft via a belt or chain drive.


Centrifugal Supercharger:

In a centrifugal supercharger, the entire setup is housed in volute shaped housing. The drive from the crankshaft is connected to a drive gear which is larger and has more number of teeth. The drive gear is meshed with a smaller driven gear with less number of teeth.



The gear ratio between drive and driven gear is to ensure that the driven gear rotates at a higher rpm. The impeller is connected to the driven gear. An internal oil gear is provided to run the oil pump for lubrication. The oil gear is meshed to the other side of the driven gear.

Working of Centrifugal Supercharger:

The drive from the crankshaft is transmitted to the drive gear, which in turn rotates the driven gear at a higher rpm. A normal supercharger driven gear rotates at a speed range of 50,000 rpm to 65,000 rpm.

The driven gear spins the impeller at the same speed. The impeller sucks the air from the atmosphere and compresses the air due to centrifugal force. In other words, as the air whirls from the center of the impeller towards the outer diameter of the impeller, it gets pressurized.

The pressurized air is sent to the intake manifold via the discharge side. A centrifugal supercharger generates very low amount of heat. It generally doesn’t require an intercooler to cool down the compressed air.



         


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