Supercharger:
Power for the supercharger can be provided mechanically by means of a belt, gear, shaft, or chain connected to the engine's crankshaft.
Working of a supercharger
Superchargers are basically compressors/blowers which takes air at normal ambient pressure & compresses it and forcefully pushes it into engine. Power to the compressor/blower is transmitted from engine via the belt drive.
The addition of extra amount of air-fuel mixture into the cylinder increases the mean effective pressure of the engine. An increment in MEP makes the engine produce more power. In this way, adding a compressor to the engine makes it more efficient.
Types of superchargers:
Centrifugal superchargers:
These are commonly used in the vehicles & are powered by the engine via a belt-pulley system. The air-fuel mixture enters the impeller at the centre. The air is then passed through diffuser, which increases the pressure. Finally the air makes it way through the volute casing to the engine.
Root's type supercharger:
Root's type contain two rotors of epicycloid shape. The rotors are of equal size inter-meshed & are mounted and keyed on 2 different shafts. Any one shaft is powered by the engine via a V-belt or gear train (depending on the distance). Each rotor can have 2 or more than 2 lobes depending upon the requirement. The air enters through the inlet & gets trapped on its way to outlet. As a result, pressure at outlet would be greater than the inlet.
Vane type supercharger:
A number of vanes are mounted on the drum of the supercharger. These vanes are pushed outwards via pre- compressed springs. This arrangement helps the vane to stay in contact with the inner surface of the body.
Now due to eccentric rotation, the space between two vanes is more at the inlet & less at the outlet. In this way, the quantity of air which enters at the inlet decreases it's volume on its way to outlet. A decrease in volume results in increment of pressure of air. Thus the mixture obtained at the outlet is at higher pressure than at the inlet.
Advantages of Supercharging:
1. Higher power output. This was whole point of. studying & installing superchargers.
2. Reduced smoke from exhaust gases. The extra. air pushed into cylinder, helps the air to complete combust leading to lesser smoke generation.
3. Quicker acceleration of vehicle. Supercharger starts working as soon as the engine starts running. This way the engine gets a boost even at the beginning leading to quicker acceleration.
4. Cheaper than turbocharger.
Limitations:
• Draws power from engine. Though the overall mechanical efficiency is increased but it consumes power from the engine. The same job is done by a turbocharger without consuming extra power.
• Increased heat generation. The engine should have proper heat dissipation systems as well as it should be able to withstand thermal stresses.
• Induces stress. The engine must hold up against the high pressure & bigger explosions generated in the cylinder. If the engine is not designed considering these stresses, it may damage the piston head.
Limitations:
• Draws power from engine. Though the overall mechanical efficiency is increased but it consumes power from the engine. The same job is done by a turbocharger without consuming extra power.
• Increased heat generation. The engine should have proper heat dissipation systems as well as it should be able to withstand thermal stresses.
• Induces stress. The engine must hold up against the high pressure & bigger explosions generated in the cylinder. If the engine is not designed considering these stresses, it may damage the piston head.
