The diesel engine is a heat engine having alternative internal combustion occurs by self-ignition of fuel due to high temperatures resulting from compression of air within the cylinder, according to the principle of the diesel cycle. It differs from the gasoline engine using diesel fuel. It has been one of the most widely used since its creation.The diesel engine was invented in 1893 by German engineer Rudolf Diesel, MAN employee of the firm, which in those years was already in the production of engines and vehicles heavy load range.Rudolf Diesel engines studying high thermal efficiency, with the use of alternative fuels in internal combustion engines. His invention cost him dearly, because of an accident that caused injury to him and his collaborators and that almost cost him his life because one of their experimental engines exploded.Diesel worked for years to use fuels other than gasoline, based on principles of compression engines without spark ignition, whose origins date back to the steam and having a greater benefit. So it was that in the late nineteenth century, in 1897, MAN produced the first engine as studies of Rudolf Diesel, finding for its operation, a particularly volatile fuel, which in those years was used, the light oil, known as fuel oil was used to light the street lamps.CONSTITUTIONFour-stroke diesel engine is basically formed of the same parts as a gasoline engine, some of which are:ArosEngine Blockbuttcrankshaftsteering wheelpistonCamshaftvalvessump

While these are elements that although most (except plugs pre-heating and nozzles) are common components with gasoline engines can be of different design and features:injection pumpductsinjectorsTransfer pumpnozzlesGlow PlugPRINCIPLE OF OPERATIONA diesel engine operates by ignition (ignition) of fuel to be injected very sprayed under high pressure in a chamber (or prechamber, in the case of indirect injection) containing combustion air at a temperature higher than the temperature of spontaneous combustion, without spark as in gasoline engines. This is called spontaneous combustion.Initiating temperature combustion has the increased pressure that occurs in the second half of the engine compression. Fuel is injected at the top of the combustion chamber at high pressure from very small holes having the injector so that atomized and mixed with air at high temperature and pressure (700 to 900 C). As a result, the mixture is ignited very quickly. This combustion causes the gas in the chamber to expand, driving the piston down.This expansion, unlike the adiabatic gasoline engine is generating rectilinear motion through the stroke. The connecting rod transmits this motion to the crankshaft, which rotates, transforming the reciprocating rectilinear motion of the piston into a rotational movement.For auto-ignition occurs is necessary to reach the temperature of the spontaneous combustion of diesel. Cold is necessary pre-heat the oil or use heavier than those used in the gasoline engine fuels, using the oil distillation fraction fluctuating between 220 C and 350 C, which is referred to as oil or diesel in english.ADVANTAGES AND DISADVANTAGESCompared with gasoline engines, the main advantage of diesel engines is their low operating cost due to the price of fuel it needs to function (DIESEL 2). There is a growing market demand for engines of this type, especially in the area of tourism

(from the 1990s, in many European countries and more than half). Currently in small vehicles are using the common-rail system. This system provides a great advantage, since a lower fuel consumption is achieved by improving the performance thereof; lower noise (typical of these engines) and reduced greenhouse gas emissions. oneThe initial disadvantages of these engines (mainly purchase price, maintenance costs, noise and less benefits) are shrinking due to technological improvements that have been made over time, in its original design especially electronic fuel injection and improvements air supply system forced with accessories like the turbocharger. Use of a prechamber for automobile engines, similar to those of gasoline engines benefits are achieved, but the drawback of increasing fuel consumption occurs, so that the main advantage of these engines practically disappears. In recent years the price of fuel has surpassed regular gasoline by the increased demand. This has generated complaints from consumers of diesel, such as carriers, farmers or fishermen.OPERATION IN DIFFERENT TYPES OF ENGINES

In the diesel engine turbocharger is more widespread because a diesel engine works with excess air in the absence butterfly, on the one hand; As this means that as per cylinder and engine speed (rpm) much air enters a diesel cylinder.Moreover, and this is most important, the pressures achieved at the end of the compression stroke and especially during the working stroke are much higher (40-55 bars) than the Otto cycle engine (gasoline engine) (15-25 bar). This high pressure, required to reach the high temperature required for auto-ignition or auto-ignition of diesel fuel is the origin of the force of the exhaust gases, to the same regimen, per cylinder and load required by the motor is much greater in diesel gasoline.Intercooler [edit]Main article: IntercoolerAir, when compressed, heated and loses density; ie have at least the same volume of air mass, so that it is able to burn less fuel and thus, less power is generated. Furthermore, by increasing the intake temperature increases the danger of detonation, chopped, or pinging and lifetime of many components due to overheating, and overstressing of the boiler is reduced.To reduce this problem is interposed between the turbo and the intake a 'heat exchanger "or" intercooler ". This reduces the air temperature, whereby the density of it, which is introduced into the combustion chamber is increased.

On the negative side, the heat exchangers cause a pressure drop, so that the air density is decreased, although in many cases it is necessary to install one or autoignition avoid detonation.There are three types of intercoolers:Air / air: compressed air in these exchanges its heat with outside air.Air / water: compressed air exchanges its heat with a liquid that can be cooled by a radiator or, in some applications, with ice in a tank located inside the car.Cryogenic: the mixture is cooled by evaporation of a gas over an air / air exchanger.DELAY IN RESPONSEThe engines with turbocharger suffer a further delay in the disposition of the power aspirated engines (NA Normal Aspiration Aspiration or Normal) or mechanical compressor, because the turbocharger performance depends on the pressure exerted by it. This delay inertia influence group (its diameter and weight) and the manifold volume between the turbine and output exhaust gas from the cylinder.A turbocharger does not work the same way in different engine speeds. At low revs, the turbocharger does not lobby because the small amount of gas does not push hard enough. A smaller turbocharger avoids the delay in responding, but exerts less force at high rpm. Various engine manufacturers have designed solutions to this problem.A "biturbo" is a system with two turbochargers of different sizes. At low revs works only small, due to its faster response, and large works only at high revs, and exerting greater pressure.A "biturbo parallel" or "twin turbo" is a system with two small turbochargers of identical size. Being smaller as if it were a single turbocharger, have less rotational inertia, so begin to generate pressure at lower rpm and response delay is decreased.An "asymmetric turbocharger" is to put one small turbocharger on a bench (the lead in the V6 engine placed transversely) leaving the other free. The idea is not to get a great power, but the response is quick. This system was invented by the Swedish manufacturer Saab and used in the Saab 9-5 V6.A "sequential twin turbo" consists of two identical turbochargers. When there is little volume exhaust all this volume is sent to a turbocharger, and when volume increases, is divided between the two turbochargers for greater power and a shorter response time. This system is used in the Wankel engine of the Mazda RX-7.

A "variable geometry turbocharger" (VTG): consists of a turbocharger having a mechanism of "fins" called rotor blades that open and close by varying the speed of the exhaust gases entering the turbine. A lower exhaust gas flow (low speed) the passage between the blades is closed causing the gases to increase the speed when entering the turbine; a higher flow rate (high rpm) need more pace and these are opened. This allows us to have a very linear pressure work around the mode of the turbocharger. In diesel engines is very common but in gasoline engines only Porsche has developed a turbo that supports over 1000 C in the Porsche 911 turbo model (2007).