Today we will learn about superchargers and types of
supercharger used in automobiles. You have many time heard the word "supercharger" or "supercharged car" but what the exact signification or meaning of
it. Before learning about it, we should first learn the basic idea behind it or
why we need it.
The whole history of supercharger is connected with power
generation. When the engine was invented, they produces much less power. There were two ways to increase power generation of an engine. The first one is by
increasing the engine size; a bigger engine sucks more fuel and develop more
power. The other option is to draw more charge (air fuel mixture) into the engine cylinder by use of a compressor hence the engine generates more power. The later process is known
as supercharging.
The supercharging is a process of draw large amount of compressed charge (fuel air mixture) into the engine cylinder which burns and generate more power comparatively the simple one. The device which provides this compressed air is known as supercharger.
It is just a compressor which is run by the engine crankshaft. The power
transmission between engine crankshaft and this compressor is achieve by a belt
drive.
According to their design, various superchargers are
available in market. The detail description about its types is given in later
portion of this article.
Types of Supercharger:
There are mainly two types of supercharger. The first one is
known as positive displacement supercharger and other one is known as Dynamic
supercharger. The basic difference between both of them is that the positive
displacement supercharger maintain constant level of pressure at all
engine speed whereas the dynamic supercharger deliver increasing pressure with
increasing speed. This is basic fundamental difference between them. These
superchargers further subdivided as given below.
1.)Positive Displacement Supercharger:
As we discussed in early section that these superchargers deliver the same volume of charge at any engine speed or these superchargers are
not depended on speed of the engine. The major types of positive
displacement supercharger are root style and twin screw.
A.) Root style:
This design has two specially designed rotors
which rotate in opposite direction (one is clockwise and other is
anticlockwise) to compress the air. According to the rotor design this
supercharger is further subdivided into two type: Two lob rotor, three lob, four lob rotor etc. As the rotor rotate, they trap
the air by these lobs coming from suction side or inlet port and forced it
towards discharge side or outlet port. The amount of air compressed is independet on the engine speed and each time this supercharger compresses the
same amount of air.
Advantages:
- Simple design
- Best suited with high speed engine
Disadvantages:
- Pulsing airflow at low speed.
- Less efficiency.
- Heavy in weight.
- Create lots of heat due to friction.
- Back leakage at low speed.
- Provide same amount of air at both low and high RPM.
B.) Twin screw supercharger:
As the name implies, this type of supercharger have two
screws which rotate in different direction. One of the screw rotate
clockwise and other one is anticlockwise direction. The working of this
supercharger is same as root type. It also sucks air from one side and
delivered it to outlet port. This device provide smother air flow
comparatively root style.
Advantages:
- No back leakage problem.
- Provide smother air flow.
Disadvantages:
- High heat generation due to friction.
- Noisy in operation.
Dynamic Supercharger:
As we discussed earlier, these type of supercharger gives
increasing air pressure as increasing engine speed. The supercharging effect in
this type is highly depended on the engine speed. It also subdivided into
following types.
A.) Centrifugal Type
As the name implies this type uses centrifugal force to
compress the air. The design of this supercharger is same as the centrifugal
compressor. It has a impeller which is connected with the crankshaft with the
help of belt drive. When the engine rotates, it makes rotate the impeller which
sucks the air from one side. The centrifugal action acts on this air which
increase its kinetic energy and delivery it to a diffuser. The air enter into
the diffusion have high velocity at low pressure. The diffuser converts this
high speed low pressure air to low speed high pressurized air. This high
pressurized air then sent to the engine.
Advantages:
- It is small in size.
- High efficiency.
Disadvantages:
- The amount of air is not fixed.
B.) Axial flow
C.) Pressure wave
This is all about types of supercharger. If you have any
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