Audi A3

Since 1997 of release

Repair and car operation

Audi A3
+ The maintenance instruction
+ Current leaving and service
+ The engine
+ Systems of cooling, heating
- The power supply system and release of the fulfilled gases
   + The power supply system
   + System of injection of fuel
   - System of injection of the diesel engine
      Direct injection
      Removal and installation of atomizers
      Check and adjustment of the beginning of injection ТНВД
   + System of release of the fulfilled gases
+ Engine electric equipment
+ Manual box of a gear change
+ Automatic transmission and models with a full drive
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment
+ Electroschemes

System of injection of the diesel engine


At work of the diesel engine in its cylinders pure air which is compressed to a high pressure is soaked up. Thus air temperature rises to 700 - 900°С, exceeding temperature of ignition of diesel fuel. Fuel is injected into the cylinder with some advancing and ignites. Thus, spark plugs for fuel ignition are not used.

Fuel is sucked in by the fuel pump of a high pressure (ТНВД) directly from a tank. In ТНВД fuel is compressed to pressure necessary for injection. Injection is carried out in an order similar to an order of ignition in the petrol engine.
For reduction of a share of harmful substances in the fulfilled gases diesel engines have diesel oxidising каталитический the converter. Simultaneously the system recycling provides essential decrease in the fulfilled gases the maintenance of oxides of nitrogen. It is reached thanks to giving of the fulfilled gases to air soaked up by the engine that provides decrease in concentration of oxygen in air, arriving in engine cylinders. It leads to a delay of ignition and to lower temperature of combustion that as a result reduces formation NOx. Process recycling the fulfilled gases should be dosed out precisely however, deposit issue otherwise increases. For this purpose the quantity of sucked in air is defined by a measuring instrument that allows the electronic device to operate process recycling.

At the cold engine the temperature of compression of air appears insufficient for fuel ignition. Preliminary heat in this case is required. For this purpose in each cylinder of the engine the electric candle накаливания is established.
Duration of heat depends on temperature of external air and is regulated by the special relay.

Fuel injection in cylinders can be carried out in three ways: through the prechamber, the vortical chamber or it is direct in the combustion chamber.

At prechamber injection diesel fuel is injected into the prechamber of the corresponding cylinder. The hot fuel mix ignites at once. However the volume of the oxygen containing in the prechamber, is sufficient for burning only parts впрыснутого fuel. The remained not burnt down part of fuel under the influence of pressure of combustion is thrown in the basic chamber of combustion where there is a full combustion of fuel.

At вихрекамерном injection fuel is injected into the chamber separated from the basic chamber of combustion. Difference from prechamber injection is other performance of the connecting channel between vortical and basic chambers. Here at compression in the vortical chamber there is a strong air turbulence that promotes good mixing of air with injected fuel.

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