5.3. System of injection of the diesel engine
During the operation of the diesel engine in its cylinders clean air which contracts to high pressure is soaked up. At the same time air temperature rises to 700 - 900 °C, the exceeding temperature of ignition of diesel fuel. Fuel is injected into the cylinder with some advancing and ignites. Thus, spark plugs for ignition of fuel are not used.Fuel is sucked in by the fuel pump of high pressure (FPHP) directly from a tank. In TNVD fuel compresses up to the pressure, necessary for injection. The injection is made as it should be, similar to an ignition order in the petrol engine.
For reduction of a share of harmful substances in the fulfilled gases diesel engines have the diesel oxidizing catalytic converter. At the same time the system of recirculation provides essential decrease in the fulfilled gases the content of oxides of nitrogen. It is reached thanks to supply of the fulfilled gases to the air which is soaked up by the engine that provides decrease in concentration of oxygen in air, coming to engine cylinders. It leads to a delay of ignition and to lower temperature of combustion that as a result reduces formation of NOx. Process of recirculation of the fulfilled gases has to be dosed however precisely, otherwise issue of a deposit increases. For this purpose the amount of the sucked-in air is defined by the measuring instrument that allows the electronic device to operate recirculation process.
At the cold engine temperature of compression of air is insufficient for fuel ignition. In this case preliminary heat is required. For this purpose in each cylinder of the engine the electric glow plug is established.
Duration of heat depends on temperature of external air and is regulated by the special relay.
The injection of fuel in cylinders can be made in three ways: via the precamera, the vortex camera or directly in the combustion chamber.
At prechamber injection diesel fuel is injected into the precamera of the corresponding cylinder. Hot fuel mix at once ignites. However the volume of the oxygen which is contained in the precamera is sufficient for burning only of a part of the injected fuel. The remained not burned down part of fuel under the influence of pressure of combustion is thrown in the main combustion chamber where there is a full combustion of fuel.
At vortex-chamber injection fuel is injected into the camera separated from the main combustion chamber. Difference from prechamber injection is other performance of the connecting channel between vortex and main cameras. Here at compression in the vortex camera there is a strong air turbulence that promotes good mixing of air with injectable fuel.