5. For diesel engines, there are three fuel injection methods: swirl chamber injection, pre-chamber injection and direct injection.
6. With vortex chamber and pre-chamber methods, fuel is injected into the preliminary chamber (fort chamber) of the corresponding cylinder where it mixes with air and creates a ready-made working mixture, while part of the fuel immediately ignites and burns out. Due to the turbulence of the air flow and heating during the combustion of part of the fuel, the working mixture becomes more homogeneous and heated. This ensures the completeness of combustion of fuel when it enters the cylinder and more «soft» engine operation. The main disadvantage of these injection methods is the complexity of the engine design. Direct injection continues to be the most common and most economical.
7. With direct injection, fuel enters directly into the combustion chamber through the injector nozzle. Each atomizer has, as a rule, 4-6 very thin holes, drilled at different angles, through which the fuel is sprayed in specially given directions. Usually there is a swirl chamber in the bottom of the piston. Swirl chambers can have a different shape, which is consistent with the directions of fuel spraying, contributes to better mixture formation and more efficient combustion of the working mixture. This method is used on all diesel engines considered in this Manual.
8. On Y20DTH/Y22DTR engines, fuel is drawn from the fuel tank by the high pressure fuel distribution pump (injection pump). The injection pump creates the high pressure required for injection (about 900 bar) pressure and supplies fuel through the nozzles to the engine cylinders in the order of the cylinders. First, a small amount of fuel is pre-injected, which, when burned, prepares the conditions for the injection of the main portion of the fuel. This results in more «soft» and uniform combustion of fuel, as on engines with swirl chamber injection.
9. On Z19DT engines (H) fuel is drawn from the fuel tank by the electric fuel pump and delivered to the high pressure fuel pump (injection pump). For direct injection on these models, a system is used «Common Rail» - common for all cylinders fuel distribution line (see resist. illustration). This system relieves the injection pump from the function of distributing fuel, which allows the pump to create a higher (approx. 1600 bar) pressure, - this contributes to a very fine atomization of the fuel, due to which the process of mixture formation in the cylinders improves and the efficiency of combustion of the working mixture increases. fuel distribution line (Common Rail) made in the form of a manifold, from which fuel is supplied to individual nozzles.
16.9 Common rail injection system (on the example of Z19DT engines (H)):
1. Fuel filter; 2. Pressure regulator; 3. High pressure fuel pump; 4. Fuel distribution line (Common-Rail); 5. Pressure sensor; 6. Nozzle; 7. Fuel tank; 8. Electric fuel pump; 9. Electronic engine control module: dotted arrows direction of electrical signals, short arrows direction of fuel flow
10. On the 6-cylinder Y30DT engine, direct injection is also via the Common-Rail system, but the fuel from the fuel tank is drawn by the high pressure fuel pump. The injection pump drive of this engine is carried out from the crankshaft by means of a gear mechanism.
11. On all engines, before fuel enters the injection pump, it is cleaned in the fuel filter from contaminants and water. The engine is equipped with injectors with electromagnetic controls that receive signals from the engine management system, which regulates the amount of fuel supplied to the cylinder.
12. High pressure fuel pump does not require special maintenance work. All moving parts of the fuel system are lubricated with diesel fuel.
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