Turbocharger design & working principle

Turbocharger: Construction & Working Explained with Diagrams

Find out How a Turbocharger works:

A turbocharger is a turbine-driven, forced induction, mechanical device. It compresses the incoming air and pumps it into the engine cylinder at high pressure. Thus, it increases engine’s efficiency and power output by about 30% to 40% as compared to naturally aspirated engines.

Turbocharger construction
Turbocharger construction

Both, the Petrol and Diesel engines use turbo-chargers to enhance power. However, they considerably differ in key areas such as operating temperatures, combustion pressures, the volume of air and operating RPM range. Furthermore, a Supercharger is a similar device which works on the same principle. However, it uses engine power.

Turbocharger Construction Details:

A turbo-charger mainly consists of two wheels. It has a turbine wheel and a compressor wheel which fit at opposite ends on the same shaft. The outgoing exhaust gases rotate the turbine wheel while on their way out. As the turbine is fixed to the shaft, it rotates the shaft. Furthermore, the compressor wheel fitted on the other end of the shaft also rotates with the shaft and acts as a suction fan. The rotating compressor wheel creates the suction of the incoming air and then pumps it into the engine cylinders. In fact, a typical turbo-charger spins at very high speeds, ranging from 30,000 to 1,25,000 rpm.

Turbocharger circuit
Turbocharger circuit

The compressor pumps up the fresh air into the cylinders at above atmospheric pressure which results in engine cylinders getting extra air. As the volume of the air grows the corresponding quantity of fuel supplied to the engine is also proportionately increased which increases power. When you compress the air, it heats up. Thus, the temperature of the air rises and it expands while reducing its density.

Hence, often, manufacturers use an Inter-Cooler or a 'heat-exchanger' to cool the air before it enters the engine cylinders. So, manufacturers refer to these engines as 'Turbo-Charged Inter-Cooled' or ‘TCIC’. Turbochargers are designed and calibrated to different engine sizes & constructions such as Direct InjectionIn-Direct Injection, and Common Rail Direct Injection technologies in diesel engines as well as the MPFi and GDI systems in Petrol engines. Hence, they cannot be directly interchanged.

Turbocharger Components:

1. A radial inflow Turbine Wheel
2. A Centrifugal Compressor
3. The Center hub / rotating assembly
4. Housing

Turbocharger parts
Turbocharger parts

Turbo-chargers have two main technologies which are:

1. Fixed Geometry
2. Variable Geometry

These days, modern diesel engines feature a turbo-charger with Common Rail Direct Injection (CRDi) system which improves the performance of diesel engines. Furthermore, some advanced engine designs comprise ‘Bi-Turbo’ or ‘Twin-turbo’ technology in a six / eight-cylinder engine for superlative engine performance. This design implements two separate units operating either in a sequential or in a parallel arrangement. Volvo’s S80 T6 car has such an engine that uses Twin-Turbo technology. BMW 7 Series' 3.0-liter engine has an advanced Triple-Turbo technology.

Advantages of a Turbocharger:

1. Higher power output
2. Improved power to weight ratio
3. Lower emissions

Difference between Petrol & Diesel Turbocharger:

Turbocharger Diesel vs Petrol
Turbocharger Diesel vs Petrol

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