Hyundai Elantra

since 2000-2004 of release

Repair and car operation

General information about system of injection of "Common Rail"

Arrangement of elements of system of injection of "Common Rail" on the diesel 4-cylinder engine

Basic element of system of injection of fuel is the fuel pump which is established on all diesel engines. Pressure of injection to the 1350th bar is necessary for increase in capacity to 160 kW on the cylinder.

Many systems of injection of diesel fuel, in particular, direct injection (Dl) are in recent years developed. The task not only increases in engine capacity, but also fuel consumption and noise reduction and decrease in toxicity of the fulfilled gases was thus pursued. In comparison with earlier used systems the system of injection of Bosch "Common Rail" fuel (storage fuel system) for direct injection of fuel (Dl) provides higher flexibility at adaptation to a power supply system of the diesel engine, for example:

– an extensive scope (for automobile and commercial cars with target capacities of 30 kW on the cylinder, together with for lorries of big loading capacity, locomotives and vessels with target capacities of 200 kW on the cylinder;
– high pressures of injection of fuel to the 1400th bar;
– injection changes at engine start;
– possibility of control, main and late injection;
– provides compliance of pressure of injection to an operating mode of the engine.

Functioning of system of injection

The distinctive characteristic of system with the general Common Rail pipeline (storage fuel system) consists in division of the knot creating pressure, and knot of injection of fuel.

The basis of system is made by the tank (accumulator). Pressure of injection does not depend on amount of injected fuel and frequency of rotation of a cranked shaft of the engine. The fuel stock under pressure is in the accumulator of a high pressure of "Common Rail" and is ready to injection. The amount of injected fuel is determined by the requirement of the driver, and pressure of injection pays off the control unit (ECU) on the basis of information from various sensors. ECU during precisely established moment transmits a signal of excitement to the nozzle solenoid, meaning the beginning of supply of fuel. The amount of injected fuel is defined by the period of opening of a spray and pressure in system. ECU and sensors of system of injection of fuel include:

– ECU;
– sensor of frequency of rotation of a cranked shaft;
– sensor of provision of a camshaft;
– sensor of provision of a pedal of an accelerator;
– the pressure sensor in system with the general pipeline;
– the sensor of temperature of cooling liquid;
– measuring instrument of a consumption of air.

On the basis of information from above-mentioned sensors and the requirement of the driver (the provision of a pedal of an accelerator) ECU defines the instant operational characteristic of the engine and the car as a whole. The block processes the signals developed by sensors and transferred on communication lines, and on the basis of this information operates injection system in a mode of the opened or closed contour. Frequency of rotation of a cranked shaft of the engine is measured by the sensor of frequency of rotation of a cranked shaft, and the sensor of provision of a camshaft defines sequence of injection of fuel (length of a phase). The electric signal from a potentiometer of provision of a pedal of an accelerator transmits ECU a signal about pressing degree the driver on an accelerator pedal.

The measuring instrument of a consumption of air transmits ECU a signal with data of rather instant stream of air that allows to calculate process of complete combustion of fuel with the minimum content of harmful substances in the fulfilled gases. As the engine is equipped with a turbokompressor and adjustment of increase in pressure of pressurization, the additional sensor also measures this pressure. At low external temperature and the cold ECU engine defines the moment of injection and other parameters corresponding to a special operational mode. Depending on the car and increase of requirements to safety and comfort for information transfer of ECU additional sensors can be used. In drawing it is set an example the diesel 4-cylinder engine with system of injection of Common Rail fuel.

Main functions

The main functions of system consist in ensuring injection of demanded amount of fuel during strictly certain moment and under necessary pressure. It provides not only smooth operation of the diesel engine, but also economic consumption of fuel.

Additional functions

Additional functions in the closed contour and management function without feedback serve in an operating mode for reduction of toxicity of the fulfilled gases and fuel consumption and are used for improvement of safety, comfort and convenience.

For example: A retsirkulyatsiya of the fulfilled gases (EGR), adjustment of pressure of pressurization of air, gear shifting, an electronic immobilizer etc. The CAN system provides data exchange with other systems of the car. At diagnostic check of the car it is possible to take the data being in a reserve of data of system.