9.1. General information

The diesel engine is a piston engine with spontaneous ignition from compression. Its fundamental difference is preparation of gas mixture of fuel with air in cylinders.
In the diesel engine fuel and air move separately. At first in the cylinder air is soaked up, then it contracts and only after that at the end of a step of compression fuel is injected.
Spontaneous ignition of fuel is followed by sharp, spasmodic increase in pressure in the cylinder – usually noisy, "rigid" operation of the diesel engine is explained by it. In low-reverse diesel engines of large working volume which are used by trucks this shortcoming is shown to a lesser extent, and with it are reconciled. In diesel engines of cars try to get rid of it use of the vortex camera, or precamera, – a small compartment of the combustion chamber into which fuel is injected. There it ignites, partially mixes up with air then extends on the main volume of the cylinder. This way reduces "rigidity" of operation of the engine a little, but reduces its thermal efficiency and fuel profitability. For smoother ignition of fuel the two-level injection and the difficult electronic scheme of management are used.
Characteristic of diesel engines is existence in the fulfilled gases of firm particles – soot. Good combustion of diesel fuel requires considerable, even superfluous, amount of air.
Extent of compression of the diesel engine is twice higher, than petrol. High, not less than 14 (reaches 25), extent of compression is necessary for increase in air temperature in the cylinder up to the size sufficient for fuel ignition. Usually in diesel engines extent of compression makes 21–22 and is limited only to strength characteristics of the engine.
In diesel engines it is much more difficult than the device for supply of fuel, than in petrol. Their complexity is defined first of all by what should be injected very small, on only several milligrams, portions of fuel on Wednesday with high pressure. For injection and dispersion of fuel, and also for distribution of its particles on the volume of the combustion chamber nozzles serve. High extent of compression demands use of the corresponding fuel pumps: pressure in a snivel of a nozzle has to reach several hundred bars. All this complicates and noticeably raises the price of a fuel supply system and, respectively, the diesel engine.
Fuel from the fuel tank moves to nozzles the fuel pump of high pressure.
For reduction of amount of the harmful substances which are contained in the fulfilled gases on cars with diesel engines establish oxidizing catalytic converter. For this purpose also the system of recirculation of the fulfilled gases is used. Addition of the fulfilled gases in working mix for decrease in extreme temperature of combustion allows to reduce in them emissions of nitrogen oxides (NOx).
Three ways of injection of diesel fuel in engine cylinders are known: through a forkamer, the vortex camera and direct injection.
At injection of diesel fuel through a forkamer fuel is sprayed on it and instantly ignites. Because of insignificant amount of oxygen in a forkamer only a part of fuel burns down, other part is forced out from forkamer in the engine cylinder where burns down completely.
At injection of fuel via the vortex camera process of combustion of fuel happens in the same way, as well as at injection of fuel through a forkamer. Difference consists in a form and the sizes of the channel connecting the vortex camera to the combustion chamber. At injection of fuel in the vortex camera it mixes up with air much better, and process of combustion proceeds more smoothly.
At direct injection fuel comes to the combustion chamber at once. The fuel pump gives fuel under pressure of about 900 bars, and the injection of fuel is made in two stages.
Use of two-channel fuel nozzles gives the chance to make initial injection of an insignificant part of fuel therefore fuel combustion process improves, and process of combustion proceeds more smoothly. The amount of injectable fuel is regulated by an electronic control system of the engine on the basis of information from sensors.
The air stream coming to the engine in inlet canals twists on a spiral therefore process of combustion in engine cylinders improves. Besides at the same time launch of the cold engine is facilitated, and preliminary warming up of the engine needs to be carried out at air temperature below -10 °C.
Before receipt in the fuel pump of high pressure fuel passes through the fuel filter in which from it also water which needs to be merged periodically separates.
The drive of the fuel pump is carried out by a gear belt. Its internal mobile details "are greased" with diesel fuel.
The power supply system of the car consists of the multisection fuel tank, pipelines, the fuel filter, the toplivopodkachivayushchy pump, the fuel pump of high pressure and nozzles.
The fuel tank is located under the bottom in a back part of the car. Ventilation of the fuel tank is carried out through the closed system of removal of air. At ventilation of couple of fuel from a tank are caught by a canister with absorbent carbon – an adsorber.

Preventions
Do not allow hit of diesel fuel on cooling system hoses. Hoses which the long time influenced diesel fuel need to be replaced.
The power supply system of the diesel engine is especially sensitive to pollution therefore at work on system observe the maximum purity. Before separation of fuel-supply lines carefully clear them of dirt. During removal of elements of system close open places lint-free fabric.
Do not use compressed air for cleaning of the elements of system established on the engine.
When checking work of nozzles never hold up hands or any part of a body under the fuel stream leaving a nozzle. Fuel comes out a nozzle under high pressure and can get inside through skin.
For protection of eyes against hit of fuel in them use points. At hit of fuel on skin wash out its large number waters.
Establish only pure elements of a power supply system.
   Take spare details from packing just before their installation.