After some market and technology, this week Auto for Dummies goes into detail about one of the most used components in modern internal combustion engines: the turbocharger. For friends simply "turbo", we present this inevitable component following the typical Anglo-Saxon style of the 5W (Who, What, When, Where, Why) adapted to describe its peculiarities.
Who invented the "turbo"?
The turbocharger is a mechanical component born over 100 years ago by the Swiss engineer Alfred Büchi. Lived at the turn of the 900s, this inventor was fascinated by the idea of increasing the efficiency of combustion engines, just introduced in steam engines and in the wake of Ford's great automotive successes on the other side of the ocean.
Patent number 204630, received on November 6, 1905 by the then German trademark and patent department, described a "solution capable of capture the residual heat of combustion through a compressor and an axial turbine ”connected to the power production mechanism. The idea itself was simple even if at the time the materials and techniques necessary to apply this technology were still lacking.
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Other patents followed that integrated the idea of the turbocharger in the newly born diesel engines and for applications other than the automotive sector such as naval, aeronautical and industrial. In 1930 this technology began to be applied to the world of car competitions and since then the “turbo” has always been a point of reference for expanding the potential of engines by making the most of the energy produced in the combustion chamber.
Why was it successful and what are the benefits
The principle of operation of a classic car engine is relatively simple. The chemical bonds of the fuel can be "broken" by a reaction called combustion. In order for this process to take place, a suitable fuel (diesel, petrol, gas…) and a substance, called comburent, is required, capable of carrying out the transformation; the oxygen present in the air is just right for us.
This is how the engine draws in fresh air from the outside, burns it under controlled conditions inside the combustion chamber (the piston housing) and produces an explosive mixture capable of moving all the mechanisms present. It is easy to think that something that burns produces heat and, in the case of a naturally aspirated automotive engine, i very hot residual gases they are directly discharged into the atmosphere.
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According to the basics of physics, among all the first law of thermodynamics, heat is a form of energy and as such it can be transformed through suitable solutions into mechanical work. If the main cylinder-piston mechanism is able to exploit the high pressures to supply torque to the wheels, the same cannot be said for recovering the residual energy in the form of heat from the burnt gases.
This is where the turbocharger comes into play and its ability to convert residual heat in the exhaust into additional mechanical energy capable of sucking in and "pushing" a extra amount of air fresh inside the engine.
How energy recovery takes place
It will seem like magic but this particular conversion is all science and technology. The hot fumes expelled from the engine reach temperatures even over 700 ° C and it is a real shame to miss the opportunity to use them. Once the materials capable of withstanding these temperatures were discovered and made cheaper, the step to construct the turbocharger was short.
Before being released into the atmosphere, hot gases are passed through one turbine, device capable of converting the kinetic energy (speed) and enthalpy (temperature) of the gas into mechanical energy capable of turning the turbine impeller. This impeller is nothing more than a small wheel specially designed inside a scroll. The turbine mechanism is directly connected to another component, mechanically similar, said compressor which works exactly the opposite.
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If the turbine transforms the energy of the hot gases into "rotation", the compressor transforms the "rotation" of the turbine into pressure - hence the term compressor - capable of forcibly suck in air external. More air means more chances of burning fuel and therefore more power. With the same engine capacity, consumption certainly increases, however this is compensated by the fact that the abundant thermal energy that is not normally used escapes.
Where the turbo is used
Today we hear about nostalgia for new aspirated engines turbo-diesel e turbo-petrol; there are entire books, academic or otherwise, which discuss the subject by comparing the advantages and disadvantages of the different solutions; here we limit ourselves to taking the discourse “away”.
As we explained to you in a recent article by Auto for Dummies, the diesel fuel needed to power a diesel engine is less valuable and refined than a petrol. It is no coincidence that the turbocharger was incredibly successful in the first of the two engines: in a diesel, in fact, the major temperatures and pressures produced inside the combustion chamber generate even hotter gases at the exhaust. The energy that can be obtained is certainly greater and, once money has been spent to make the robust materials with which a diesel is built, the step to couple everything to a turbocharger is short.
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In the course of the 900s, however, the most varied solutions were reached that could make this system competitive and efficient. The modern turbo-petrol engines work perfectly and variants such as the more "American" direct supercharging - without the aid of the turbocharger - always give great satisfaction in terms of power sinning instead for consumption and pollutants.
When the era of supercharging will end
Supercharging an internal combustion engine was just one of the first solutions to increase the efficiency of powertrains. Today we can find the most varied energy recovery systems: from the heat developed during braking to the springing of the suspension.
After the development of fully electric engines, the market is constantly moving towards intermediate solutions such as the hybrid and if on the one hand the combustion purists are oriented towards an engine capable of combining the advantages of diesel and petrol, the most ambitious will certainly find interesting systems such as low displacement engines combined with supercharging and electric motors suitably supported by innovative battery recharging systems.
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An uncertain future to be discovered but which, thanks to the ingenuity of great technicians and engineers, will certainly be greener and, hopefully, exciting for all lovers of the world of motors. In the next Auto for Dummies article we will deal with the most important and historic car competitions: from the first championships of formula 1, rally up to the new and selective races of Formula E.
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