Advanced Manufacturing Processes and Materials (Turbocharger)
Turbocharger is nothing but a gas compressor, which is kept in use to forced-induction of the internal combustion engine. It is a derived form of supercharger. The fundamental function of the turbocharger is to enhance the density of the air which is entering in the engine. Density is increased to produce more power.
Compressor, turbine and shaft are the core and essential parts of a turbocharger. Compressor of the turbocharger got power by a turbine and this is driven by exhaust gases of the engine. Direct mechanical drive is not used like many other superchargers.
In early days or in the days of the invention of turbochargers, it is referred as turbosuperchargers because turbochargers were derived from the superchargers by combining a turbine in the accessories of superchargers. Compressor was there in the superchargers, but turbine was not present in superchargers.
In turbochargers, a fan pump of small radius comes into the driving condition with the help of the gases which get exhausted by the engine. The main assembly parts of the turbochargers means turbine, compressor and shaft are attached in such a way that turbine and compressor shares a shaft and get attached with it.
The turbine is used to alter the exhaust heat and pressure into the rotational force and this rotational force drives the compressor. Compressor increases the pressure of the air and this pressurized air enters into the cylinders on each intake stroke. This in turn increases the volumetric efficiency of the engine and this is done by solving one of its cardinal limitations.
Only downward strokes of a piston are used in naturally aspirated automobile engine, but the pressure of the atmosphere can not be increased more than 1 atm. This thing creates a pressure difference limit in the naturally aspirated automobile engines, which limits the amount of airflow entering the combustion chamber.
But turbocharger eliminates this limit because it is designed in such manner that it increases the pressure at a particular point from where air enters into the cylinder. This in turn maintains pressure into the combustion chamber, which increases the revolution speed. This increasing speed produces high power and torque at the output of the engine.
But there is a limitation on the pressure in the turbocharger. Pressure should not cross its critical limit, otherwise explosion and physical damage may occur in the engine. To avoid such type of conditions an arrangement has been made there in the turbocharger. In this type situation intake pressure is being controlled by venting excess gas and this facility is being provided by wastegate functionality.