Operating Principles - SSANGYONG Rodius 2013 Manual

4. OPERATING PRINCIPLES

The E-VGT is designed to get more improved engine power in all ranges by controlling the turbine as
follows:
1) How it Works at Low Speed
Normal turbocharger cannot get the turbo effect because the amount of exhaust gas is not enough
and the flow speed is slow in a low speed zone, but VGT allows the flow passage of exhaust to narrow,
resulting in increasing the flow speed of exhaust gas and running the turbine quickly and powerfully.
Therefore, as VGT can intake more air than normal turbocharger, it can give the benefit of the
increased output even in a low speed zone.
Turbocharger
Control
driving
range
mechanism
At low
speed
※
Basic principle at low speed
At low speed, it utilizes the principle of venturi.
For example, when air flows through the venturi
tube, the flow speed is faster and the pressure
is lower at the point "A". In this case, if the inner
diameter of venturi is more narrowed, the flow
speed is so much faster (refer to the equation).
Turbocharger lag
The turbocharger is at idle speed when there is no load or it is in the normal driving condition. During
this period, the amount of exhaust gas passing through the turbine is not enough to turn the
compressor wheel (impeller) fast. Therefore, the intake air is not compressed as needed. Because
of this, it takes time for turbocharger to supply the additional power after the accelerator pedal is
depressed. This is called "turbocharger lag".
Control
method
The flow rate is
increased as the
Narrows the
exhaust gas passes
flow passage for
the narrow passage
the exhaust gas
→ Increased
by folding the
turbine & impeller
vanes
speed, Increased
compressive force
1914-01
Improved
Effect
performance
Improved
low speed torque
06-21