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how a turbocharger works
What is a turbocharger and how does a turbocharger work?
Cummins Turbo Technologies gives you a comprehensive guide to turbocharging....
In simple terms, a turbocharger comprises of a turbine and a compressor connected by a common shaft supported on a bearing system. The turbocharger converts waste energy from the exhaust manifold into compressed air which it pushes into the engine. This allows the engine to produce more power and torque and improves the overall efficiency of the combustion process.
 
The turbine comprises of two components; the turbine wheel and the collector, commonly referred to as the turbine housing . The exhaust gas is guided into the turbine wheel by the housing. The energy in the exhaust gas turns the turbine. Once the gas has passed through the blades of the wheel it leaves the turbine housing via the exhaust outlet area.
The speed of the engine determines how fast the turbine wheel spins. If the engine is in idle mode the wheel will be spinning at a minimal speed. As more gas passes through the turbine housing, the faster the turbine wheel rotates.
Compressors are the opposite of turbines. They comprise of two sections, the impeller or compressor wheel and the compressor housing . The compressor wheel is connected to the turbine by a forged steel shaft. As the compressor wheel spins, air is drawn in and is compressed as the blades spin at a high velocity. The housing is designed to convert the high velocity, low pressure air stream into a high pressure, low velocity air stream through a process called diffusion.
Air enters the compressor at a temperature equivalent to atmosphere; however it leaves the compressor cover at a temperature up to 200 degrees Celsius. Because the density of the air decreases as it is heated up, even more air can be forced into the engine if the air is cooled after the compressor. This is called intercooling or aftercooling and is achieved by cooling the charge air either with water or air.
The turbocharger bearing system is lubricated by oil from the engine. The oil is fed under pressure into the bearing housing , through to the journal bearings and thrust system. The oil also acts as a coolant, taking away heat generated by the turbine.
The Journal Bearings are a free-floating rotational type. To perform correctly, the journal bearings should float between a film of oil (i.e. between bearing & shaft, and bearing and bearing housing). The bearing clearances are very small, less than the width of a human hair. Dirty oil or blockages in the oil supply holes, can cause serious damage to the turbocharger.

 

 
 
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