The current popularity of internal combustion engines,
such as gasoline and diesel engines, originates from the
combination of their attractive driving performance due to
high toque levels and low fuel consumption. The decisive
role of these characteristics has led to the development of
charger technology, resulting in a remarkable increase in
power density and mean effective pressure. Turbo charging
technology has been widely used in engines for different
applications, ranging from small vehicles to large marine
vessels, thanks to its technical advantages such as no
demand for driving power from the engine and excellent
charging effects during sac operation at mid to high engine
speeds. However, there is a response time delay, especially
for passenger car turbochargers, which can be problematic
since mot driving is done under downtown conditions at
mid to low engine speeds resulting in a "turbolag" when
there is sudden acceleration[6].
In recent years, the motor vehicle industry aims at the
small sized and high power density engine, while
downsizing (small size and weight saving) and measuring
the improvement in fuel consumption, and cleanization.
The demand of economical minivehicle increases in
recent years from such a background by low fuel
consumption, and by the time it will especially exceed 30
percent of the automobile total number of possession in
Japan of 2005, will grow up. However, power of a
minivehicle is insufficient and there is indication of the
user that acceleration power is weak and unsatisfactory,
especially at the time of a start dash, gradability, and
passing, etc. For the reason, Auto makers taking out with
the high-output car.(as shown in below figure)[3].
Fig. 1. Share of mini vehicle[3]
A supercharger is a belt or gear driven air pump used to
increase the air density at the inlet of an engine to generate
more power. A supercharger is connected directly to the
crankshaft by a belt and therefore can provide an
immediate boost and horsepower on demand[1].
As compared with the turbocharger engine, a
supercharger is mechanically driven by the engine
crankshaft. Since the engine speed and supercharger speed
are in a fixed ratio to each other, boost pressure change
with engine speed much more rapidly than in the case of a
turbocharged engine[2]