Petrol engine

Assignment
The petrol engine shall convert the chemical energy contained in the fuel with degree of effectiveness as large as possible and low pollutant ejection into mechanical energy. It shall connect a favourable torque with a high performance at an engine run as low-vibration as possible at higher rotational speeds in the lower engine speed range. A considerably higher trick fortune and a quick reaction to movements of the driving pedal is still demanded at the petrol engine opposite the diesel engine in addition to a soft engine run. The petrol engine opposite the diesel engine has a higher wear besides the higher fuel consumption at the cold start. The fuel results on the cold cylinder walls and washes the engine oil there. It in addition thins it down and worsens the smearing qualities with that. The wear at a cold start shall 20? degrees Celsius correspond to it of approx. 200 km of car rail journey.

Function
The fuel is added to the air almost exclusively before reaching the cylinder sprayed fine (outer mixture formation). A certain mixing ratio is adhered to exactly in almost all operating states. After the compression the burning is started by an electrical ignition system. The petrol engine also is called Otto engine unlike the diesel engine. Nicolaus August Otto, however, has not invented approximately the petrol, but the four-stroke engine. Since there is this, however, also as a diesel engine, the expression Otto engine for the petrol engine is actually wrong like so many concepts in motor vehicle technology.

Important
The characteristic of the petrol engine remains the fuel air mixture is from outside ignited also at direct injection.

Diesel engine

Assignment
The diesel engine shall convert the chemical energy contained in a very igniting willing fuel with degree of effectiveness as high as possible and low pollutant ejection into mechanical energy.
Its advantages are:
- high torque at low rotational speeds
-opposite the petrol engine still a greater life time particularly at frequent short-distance traffic.

Function
Fresh air is drawn in. Without boost a minimum compression of 18 : 1 required 30 bar for a sure burning. The fuel is injected into highly heated air at side combustion chamber procedures with approx. 130 bar and at direct injection with a considerably higher pressure. Without an electrical ignition system the burning is immediately carried out (self ignition). The pressure is caused by mechanical high pressure pumps and reaches injectors over nozzles or at Common Rail and pump injector directly into the combustion chamber. Air is enough available unlike the petrol engine also without boost at all operating ranges. Harmful nitric oxides (NOx) result because of this high burning temperatures. The shorter time of the mixture formation and the approx. 13% higher C content of the derv opposite petrol also increases the ejection of soot (particle). The middle work pressure (mean average value over all 4 strokes) can exceed 10 bar at modern diesel engines because of the higher compression and the higher burning final pressure. Since the diesel engine condenses more highly, it also authorizes more room for the waste gases in the operating cycle. At the diesel engine, therefore the waste gas temperatures are C 600? degrees Celsius less than at the petrol engine with 500?. In the cold state igniting delay appears at the diesel engine. The period of time is meant with that between injection and burning of the fuel. This also leads at modern engines for considerably higher development of the noise. One afterglow facilities can soothe this disadvantage.



Common Rail

It runs just like a multi-point system for petrol engines. The splashes are electromechanical and get steered by an electronic operation which determines the moment and the opening duration. Of course all this was adapted to the gas oleograph, which stands here at 1350 bar (a system is developed at the moment, which will reach 1700 bar); e.g. the splashes are steered by 50 volt impulse unlike the 12 volts of the petrol engines to overcome this pressure where the pressure on only 3 -4 bar remains. The advantages get visible both in the design phase and in the sales. It is more simpley to adapt a common rail System to a new machine drive (the right tuning of the chipset is enought) than to adapt the classic Bosh VP44 rotating Pump (which gave new life to VW, Audi, Seat, Volvo, Opel).

Pump injector (selective injection): By opening and closing of the bypasses the control system is able to measure the gasoil out with enormous precision and reconciles pre-splashes during the hammer blow added so that the heating of the gas oil which soon afterwards is imported can be accelerated. With such a high pressure the pump splash has the advantage that the burning improved what and reduced the harmful waste gases and the consumption it the gasoil in very fine particles nebulized. The space-consuming size is the present disadvantage of this system. The dimension which is needed by the engine head which would be necessary to be able to use more as two valves per cylinder, steals the place for the valves. The diesel engine needs at least a regulation of the neutral and particularly the final speed since unlike the petrol engine air surplus still works it for maximum speed with mind. 40%, too. Both the smallest car diesel engines and ship diesels reach a thermal degree of effectiveness of max. 45%.

Digital tuner amplifier

Assignment
The digital tuner-amplifier shall take all information of the sensors, process and give corresponding signals to the actuators. It is able to communicate with other tuner-amplifiers via CAN bus. It can store, compare with firmly stored data (engine characteristics) measurements. It can in addition notice errors, store and start need run programmes. A possible new programming and the ability of modern tuner-amplifiers for the operation of the actuators (putting member diagnosis) is also important for the workshop besides the possibility for the fault and measuring judging selection. A slight check of lines, hardware connections and actuators is ensured with that.
Function
Apart from the output on a monitor and possible options like sound card and drives a modern digital tuner-amplifier is not different from the known PCs. The processing speed is, even rather even higher it can but confine and-output himself compare oneself, on data search. It contains a microprocessor a program and a datamemory and I/O units. The waste gas legislation stipulates an On board diagnosis (OBD) for motor vehicles. This supervises continuously all waste gas relevant components and functions. The On board diagnosis permanently compares the reactions of the system with the instructions of the tuner-amplifier and the signals of the sensors on its plausibility. The tuner-amplifier saves recognized bugs together with the operating conditions in the field of appearance. At the inspection the bug memory can be selected about a standardized diagnosis interface with a tester.
Machining
Modern processors are very fast. While e.g. the crankshaft of a petrol engine turns with 6000 1/min only around 1?, then in this time still more than 1000 machine instructions are possible for it. These contain e.g. the selection or placing of a numerical value or the jump over an enormous data block on the search for the correct value. Very many functions e.g. the lambdacontrol must be artificially braked (hysteresis), in order to avoid over reactions of the system. The procedures partly run off also within the processor parallel. It is for the processor thus no problem, between two ignitions all necessary data such as load, number of revolutions etc.. to take up to process within firmly given linkages and after this abundance of decisions from an enormous to determine multidimensional characteristic diagram a next ignition.

Compendium
Compendium

The RAM (Random Access Memory) is the main memory of the function calculating machine, indemtempor?re data of sensors, computing results and the real results can be filed.

All identification fields and characteristics which the computer needs for its calculations are located in the flash EPROM (EPROM = Eraseble and Programable Read Only Memory).

The control computer checks the inputsensor data and re-registrations of the putting members like injection nozzles or and fault similar on plausibility, therefore whether the received data are all right so at all. There is a fault, it reports these and this saves so in the EEPROM (Electrical Eraseble and Programable Read Only Memory), which can be selected with a diagnosis device.

For the output side the tuner-amplifier has output stages, to be able to activate various actuators.

Supercharger

The turbocharger has become a component of particularly the direct fuel-injected diesel engine almost to be not excluded any more. In the loading pressure a dream of driving a car comes true to be able accelerate powerfully out of lower speeds start by early and limitation. A waste gas turbocharger consists of a compressor and a turbine which are connected by a common wave with each other. The turbine supplies, propelled from the exhaust gases of the engine, the driving power for the compressor. For turbochargers radial compressors and centripetal turbines are in most cases used. The turbine is propelled by the exhaust gas of the engine. The compressor provides for a compressing of the fresh air. It is to produce at small numbers of revolutions a high load pressure. Therefore the maximum load pressure must be steered by a bypassventil (Wastegate). This opens the direct way to the exhaust system (evasion of the turbine) starting from a certain load pressure. This valve can be headed for pneumatically by the pressure in the suction tube or electrically (controller).

Intercooler

The intercooler lowers the high temperature arising from the boost from about 140? degrees Celsius to 90? degrees Celsius and provides a higher performance/torque by the better filling with that. If the higher performance is not used, a lower fuel consumption is possibly. Although, recently, it is more frequently installed in the diesel engine together with the turbocharger, it has an additional, important advantage for the petrol engine. The chilled air lowers the temperature in compression time. Through this the compression relationship must be reduced less strongly in proportion to that one of the sucking engine. So the advantages already mentioned above are a little bigger at the petrol engine. It works as an air air heat exchanger and function is installed between loader and engine on the sucking side. There were intercoolers at the time of carburettor technology in the motor vehicle story which became passed through of air fuel mixture. It is only air today which is cooled down. The intercooler is switched to row as in the case of the commercial vehicle with the liquid cooler, it must be ordered in any case in front of this so because cooled down on the a little lower outlet temperature here more strongly than at the liquid cooler must be. In principle, more air is pumped out task instead of drawn in and the filling improved by it into the cylinder by boost. It particularly rises engine performance without capacity increase and with diesel engine the torque in the lower speed range. Additionally fuel consumption and emissions are lowered here. High adjustment speeds and small construction units moderate the most substantial disadvantage, the retarded responsing mode. The loading can take place with the pressure of the exhaust gas stream (turbocharger), mechanical connections to the crankshaft (compressor) and g-loader or direct contact of the exhaust gases with the frischgasen and control via mechanical connections (Comprex loader). High temperatures when consolidating are reduced by an air-to-air heat exchanger (intercooler).

Common rail

Well to recognize: The high pressure pump, the rail and the injectors.

"Common Rail" means literally translated a "common line". Short: At which the fuel is formed of a collecting container on an evenly high pressure and is injected over injection nozzles steered electronically into the combustion chambers of the engine Common Rail, diesel injection technology.

The Common-Rail system also is described as a accumulator injection system. The pressure production and the fuel injection are separated at the Common-Rail system of each other (decoupled). A separate high pressure pump causes continuously pressure. Expressed differently: While conventional diesel direct fuel-injected engines are causing the fuel pressure for every injection process on the new one, it is independently built up by the injection consequence at the Common-Rail system and is in the fuel line permanently at the disposal. The pressure is stored in the so-called rail and provided to the injectors of a cylinder bench over short injection lines (see picture above). By the permanently upcoming high pressure of at most 1,350 bar (1,600 bar of 2nd generation) a very exact injection course can be obtained.
The injection time and the strength amount of substance are calculated (like the Motronic) cylinder individually and injected about solenoid valves (injectors) switching fast. This technique makes a good fuel consumption and low waste gas emissions possible. The injection is subdivided into three groups:

Pre-injection for a smooth engine run main injection for a good torque course after-injection for a little NOx value. Unlike this one and main injection becomes the fuel at the after-injection not burned but by rest warmth in the cylinder vaporizes in front of. This enriched waste gas fuel mixture is taken to the waste gas plant over the exhaust valves in ejection time. The fuel in the waste gas serves in suitable NOx catalysts as reducing agents for the nitric oxide.

The high pressure pump

It usually of three piston pumps come with a central eccentric to use. These are at save manufacturers with an element switching off provided around fuel or reduce the performance at overheating of the return pipe differently. For a short time, two plates radial piston pumps also are used by the company Delphi. These cause high pressure like the VR pump of Bosch.

Function at Audi:

The drive shaft with its eccentric cams moves the pump pistons of the three pump elements up and down sinusoidally. Fuel pushes N290 the gear wheel pump by the choke bore of the solenoid valve for fuel dosage into the fuel provision room or the smear and cooling circuit of the high pressure pump. If the promoting pressure exceeds the opening pressure of the safety valve (0th 5 ... 1,5 bar), the gear wheel pump can push fuel by the inlet valves into the pump elements at which the piston moves to below (sucking piston stroke.) If the lower dead man point of a piston is exceeded, the inlet valve closes because of the pressure drop. The fuel in the pump element cannot escape any more. It can be compressed now until after the promoting pressure of the gear wheel pump. The pressure building up opens the exhaust valve the himself when exceeding pressure situated in the rail. The compressed fuel reaches the high pressure circle. The pump element promotes as long as fuel, till the upper dead man point is reached (promoting piston stroke).

Injection nozzle

Task: The injection nozzle shall distribute and spray the fuel in the combustion chamber.

Principle: The injection nozzle is a hydraulically controlled needle valve whose needle is pushed by a prestressed feather in the nozzle holder on the valve seat. The liquid pressure spreads out in the pressure chamber, this one lies over the nozzle opening and opens the nozzle by pressure against the conical pressure shoulder lying in the pressure chamber of the nozzle needle.

In principle there are 2 kinds of nozzle: Tap nozzles with cylindrical injecting jet or with conical expand injecting jet for indirect injection (pre-chamber centrifugal chamber). Orifice nozzles with one to twelve drillings, depending upon combustion chamber for direct injection and m-procedure.

Pump nozzle

The Unit Injector-System (UIS) is a system for diesel direct injection. This technology is also known as the pump-nozzle system. In 1994 Bosch supplied he world?s first UIS for commercial vehicles. 1998 saw the appearance of the UIS for passenger cars. Its special feature is that it combines the injection pump and injection nozzle in one unit (Unit Injector).

With the UIS, a separate Unit Injector (UI) for each cylinder is installed directly in the cylinder head. The engine camshaft provides the mechanical build-up of pressure. Via tappets or rocker arms it activates a small piston inside the UI unit. The cam is shaped in such a way that the desired high fuel pressure is built up as quickly as possible in the so-called plunger chamber below the plunger. A fast-switching solenoid valve determines start and end of injection as well as the injected fuel quantity.

Fitting in the cylinder head obviates the need for the high-pressure lines required for traditional distributor injection pumps. The advantage: depending on the engine speed, the UIS can generate injection pressures of up to 2,200 bar in passenger cars. Diesel models with UIS were the first compression-ignition vehicles to achieve exhaust-gas values better than those prescribed by the EU4 regulations. Because of their high injection pressures, UI diesel engines also display an extremely good degree of efficiency and provide an extremely high torque with low fuel consumption even at low engine speeds. They are not, however, as quiet-running as Common Rail diesel engines.

Diesel particle filter

The particulate filter should eliminate the harmful particles of the Diesel engine, burn them in certain regenerative intervals, and dismiss them into the environment as innocuous components. The European Union resolutions on fine dust emissions for protecting our cities has its effect on the particulate filter, too.