What is a turbocharger and how does it work?
The turbocharger or simply said turbo is a gas compressor used for a forced inductance of air into an internal combustion engine. The aim of the turbocharger is to increase the mass of the air in the engine in order to create bigger capacity.
The turbine of the compressor is operated by its own engine exhaust. The word “turbo” comes from the Latin word “turba” which comes from the Greek word „τύρβη“ meaning “showing vanity, whirlwind, motion, riots, revolt”.
Generally speaking the working of turbocharger is as follows - a small radial air pump, powered by the energy of the engine exhaust.
The turbocharger consists of two turbines with a common shaft. One side is attached to the outgoing collector (hot side) and the other side is attached to the incoming collector (cold side). The turbocharger turbine section is a heat engine which transforms the thermal energy from the exhaustible pipes into supply which powers the compressor afterwards, presses the air and delivers it to the incoming collector with higher pressure. This leads to bigger air mass in each cylinder.
In some cases compressed air passes through an intercooler before its induction in the suction collector. The atmospheric engines use only the piston’s stroke down to create an area with low pressure in order to fill the cylinder with air through the suction valve. Since the atmospheric pressure is not more than 1 bar (approximately 14.7 PSI), ultimately in this way the quantity of air stream, led into the combustion chamber to 1 bar, is limited. This method is less efficient.
When we include the turbocharger, it increases the pressure at the point where the air enters into the cylinder with bigger mass than the oxygen mass so the pressure in the suction collector increases. The additional oxygen gives chance more fuel to be added which leads to an increase in the power of the engine torque.
Since the pressure in the cylinder shouldn’t be too high, in order to avoid detonation and disability, the reception of pressure have to be controlled by controlling the turbocharger rotating speed. The control function is fulfilled by a safety valve. This valve directs part of the exhaust gas flow far from the safety turbine. This controls shaft’s rotating speed and adjusts the air pressure in the suction collector.
By the turbocharger we obtain better use of the energy which is received by the fuel and worked off by the engine with the purpose of increasing the efficiency and the power of the engine. Otherwise this energy would be lost.
Turbocharger components. It consists of four main components: corpus, turbine (usually radial), control system and bearings.
The hot exhaust loosen the turbine from 80,000 – 300,000 revolutions, and then the big turbine from the other side (they have a common axis) achieves maximum air pressure. Of course no one bearing can stand these revolutions and because of this the turbo axis “swims” in oil, which in most cases is the oil from the engine.
Seldom is the turbocharger oil separated from the engine oil. There is an oil cooler in the cars aiming better turbo oil cooling.