To reduce the content of toxic components in the exhaust gases, diesel models are equipped with a special oxidation catalytic converter. At the same time the recirculation system (EGR), due to the dosed mixing of a small amount of exhaust gases into the air sucked into the engine and, as a result, a decrease in the concentration of oxygen in the combustible mixture, provides a significant reduction in the content of nitrogen oxides in the combustion products (NOX). Through the functioning of the EGR system, it leads to a reduction in the ignition delay and a decrease in the combustion temperature, which ultimately leads to a decrease in the formation of NOX. An indispensable condition for the organization of recirculation is the accuracy of the dosage of admixture, since otherwise the content of solid carbon particles in the exhaust gases increases (soot). The amount of air sucked into the engine is determined by a special meter, the information issued by which allows the electronic control module to control the recirculation process.
Fuel is injected directly into the combustion chambers of the cylinders.
The operation of the engine is controlled by an electronic system that is similar in structure and operation to the engine management system used on gasoline models with gasoline engines. The commands generated by the control module are based on data coming from a whole set of information sensors that continuously monitor operational parameters.
Information about the position of the crankshaft and the speed of rotation of the engine enters the control unit from the crankshaft position sensor (CKP). The inductive sensor head is located opposite the flywheel and constantly scans special reference marks applied to the surface of the latter. When the mark passes by the sensitive element of the measuring head, the sensor generates a signal pulse that is output to the control module. The marks are evenly applied to the surface of the flywheel, with the exception of a single gap corresponding to the position of 90°before TDC of the piston of the first cylinder. At the moment the flywheel passes this point, the signal pulse is not issued to the control module, which allows the latter to determine the TDC moment. According to the length of the pause / duty cycle of the pulses, the module receives information about the crankshaft speed.
Information about the amount and temperature of air entering the engine comes from absolute pressure sensors in the intake manifold (MAP) and intake air temperature (IAT). The MAP sensor is connected by a vacuum hose to the intake manifold and measures the depth of depression inside the latter. The intake air temperature is monitored by two IAT sensors, one mounted ahead of the turbocharger and one behind the intercooler (intercooler). The readings taken by the sensors are used by the control module to calculate the exact amount of fuel to be injected into the engine's combustion chambers.
The traditional coolant temperature sensor has been replaced with a head temperature sensor that provides the control module with information used in air-fuel mixture quality adjustments and injection timing calculations. In addition, the data taken by the sensor is used to control the operation of the cold engine preheating system.
The brake light/brake pedal position switch informs the control unit of the current position of the foot brake pedal. Upon receipt of signals from these sensors, the control system instantly switches the engine to idle mode and maintains it until a signal is received from the gas pedal position sensor.
The fuel supply system is organized according to the direct injection scheme. Piston bottoms are provided with vortex chambers that provide twisting of the fuel injected into the combustion chambers of the cylinders. To optimize the process of fuel combustion, the nozzles are opened in two stages (for this, two springs are placed inside each nozzle). When the injector service valve is opened, a small amount of fuel enters the internal components of the latter, providing lubrication, then returns to the fuel tank.
Preheating is also controlled by the engine control module, which provides a certain injection timing offset when the engine is cold. In addition, the control module controls the operation of the glow plugs. Glow plugs are screwed into each cylinder, are activated before starting the engine and remain hot during the entire time the crankshaft is cranked by the starter, and also for some time after the engine is started. The use of glow plugs makes it much easier to start the engine in cold weather. The activation of the driver's candles is warned by a special indicator lamp mounted in the instrument cluster (see chapter Controls and techniques for safe operation), - as soon as the lamp goes out, you can start the engine. In particularly cold weather, the plugs continue to function for some time after starting, maintaining the stability of the engine speed and reducing toxic components in the combustion products.
Note. The design of modern diesel engines is characterized by increased starting efficiency, as a result of which the need for the use of glow plugs arises only at air temperatures below -10°C.
The fuel pumped by the preliminary fuel pump is passed through the fuel filter, where it is cleaned from moisture impurities and other contaminants, try to be conscientious about the maintenance procedures, replacing the filter element in a timely manner.