Turbocharger

Bases of the turbo-loading The achievement of a combustion engine depends on air and the appropriate amount of fuel, which for the burn in the engine for the order. In order to burn 1 kg fuel completely, the engine needs approx. 14 kg of air (Lambda = 1). If the achievement of the engine is to be increased, must be supplied more air and fuel. More fuel makes however sense only if a sufficient quantity is present oxygen for the burn, otherwise fuel was only unnecessarily used. With a suction engine the achievement can be increased essentially by the fact that one increases the capacity or the number of revolutions. With a larger cylinder volume one receives however larger, heavier and thus also more expensive engines. The increase of the number of revolutions draws a set of problems, to e.g. higher wear. If one increases it nevertheless, the danger of the overstressing of individual engine construction units exists. The most elegant solution for the increase of engine performance exists therefore in compressing the intake air, i.e. the suction work is relieved of to the engine.

If the work of compressing from the use of residual energy in the exhaust gases is caused, one speaks of loading in the modern sense, how they are realised e.g. by superchargers or pressure wave loaders. Mechanically propelled compressors for loading withdraw available power from the engine, i.e. the economic overall efficiency is worse than during an exhaust gas turbosupercharge. Turbocharger in the exchange • Turbocharger supply in the exchange; i.e. new part against old part. • To the turbocharger a pledge is computed, that with return of the old part one credits. • As soon as we receive the old part, we examine it for serviceability. • The repaired turbochargers are from same quality as a new part. Sucking in the gasoline air mixture (with the petrol engine) and/or the fresh air (with the diesel engine) is with the high engine speed a problem. Between two clocks is available only very little time. Therefore flows in fewer gases, than would be theoretically possible. One calls this difference between the theoretically possible and the quantity of the incineration gas actually flowed in the volumetric efficiency. 

 

 

A turbocharger is a Zusatzaggregat of the combustion engine, which increases the volumetric efficiency of the combustion engine as external loading. The turbochargers can lead to an increase in output, without thereby the capacity or the engine number of revolutions of the combustion engine must be changed. There are thereby two types of turbochargers, i.e. the supercharger without adjustable turbines and the VTG superchargers with adjustable turbines. [Work on] operational principle of the turbocharger The turbochargers consists of a turbine and a compressor wheel, which are connected by a wave. Both the compressor and the turbine run in final housings. With the exhaust clock of the four-stroke engine the exhaust gases flow by the turbine case and accelerate the turbine on approximately 100,000 min-1. Since the turbine is propelled by the exhaust gas stream of the exhaust clock, the compressor without additional power requirement can be propelled. The rotating motion resulted from it transfers the turbine afterwards over the wave to the compressor wheel, which compresses and with small positive pressure to the intake valve of the combustion chamber promotes the intake air in the compressor stator. Since the fresh air was consolidated, it warms up in the compressor stator. In order to obtain now a higher atmospheric pressure and associated also a higher volumetric efficiency, the intercooler cools the intake air warmed up in the turbocharger.

Besides a cooled intake air has still the advantage that the combustion chamber experiences a better cooling. Sometimes also an additional air cooler is used, which likewise cools air from the recycling of exhaust gases. In the case of the turbocharger without adjustable turbines however certain problem areas result. On the one hand in the upper speed range a high turbine number of revolutions is reached, whereby air is more strongly consolidated than necessary. On the other hand the turbine in the lower speed range achieves a too small number of revolutions, whereby air is not sufficiently compressed. Thus the engine does not achieve the desired achievement, what is colloquially often called turbo-hole. In order to work against these problems, the turbochargers with adjustable turbines one developed (variable turbine geometry, VTG). In contrast to the turbocharger without adjustable turbines the VTG turbochargers the necessary compression reaches by means of the entire speed range of the engine.

This constant compression over the entire speed range reaches the VTG turbochargers by adjustable guide vanes, which lead the exhaust gas stream across the turbine. At low numbers of revolutions the cross section of the exhaust gas stream before the turbine is narrowed by guide vanes. Since the exhaust gas flows by the narrowing of the cross section faster, the turbine turns faster. Also at low numbers of revolutions the necessary load printing is produced by this effect, whereby the turbo-hole of the normal turbocharger can be gone around. Turned around at high numbers of revolutions: The guide vanes release a larger exhaust cross section, so that the necessary load printing is not exceeded. Particularly with diesel engines a supercharger is meaningful. It makes a burn possible of the fuel with same volume of the combustion chamber with higher excess air, which improves the efficiency and which fuel consumption lowers.