6.3. System of injection of fuel 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 about 700 - 900 °C that exceeds 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.
When approaching a reserve of fuel to the end, - on the dashboard the alarm lamp lights up, - it is necessary to make gas station of the car immediately.
For the purpose of decrease in toxicity of the fulfilled gases the basic equipment of all diesel models turns on the catalytic converter. At the same time the system of recirculation provides essential decrease in content in the fulfilled gases of oxides of nitrogen, a part of the fulfilled gases is mixed to the air which is soaked up in the engine that provides decrease in concentration in it in oxygen and, respectively, to reduction of a delay of ignition and fall of temperature of combustion. Minimization of education in products of combustion of oxides of nitrogen (NOH) is result of all listed processes. Process of recirculation of the fulfilled gases demands an exact dosage, otherwise contents level increases in products of combustion of coal particles (soot). The dosage is carried out due to inclusion in a chain of system of the special measuring instrument, - information arriving from the measuring instrument allows the electronic module to operate recirculation process.
The injection of fuel is made in forkamer of cylinders. TNVD has electronic control that guarantees compliance to strict modern requirements on the content in the fulfilled gases of the engine of toxic components. A brain of a control system is the electronic module which is built in pump assembly continuously analyzing the data arriving from the whole complex of information sensors:
- The sensor of provision of a pedal of an accelerator - informs control units on position of the accelerator pedal;
- The sensor of temperature of cooling liquid (ECT) - informs control units on the working temperature of the engine;
- The sensor of the measuring instrument of mass of air (MAF) - informs control units on the weight and temperature of the air which is soaked up in an inlet air duct;
- The sensor of provision of a bent shaft (CKP) - informs control units on situation and speed of rotation of a bent shaft;
- The pressurization pressure sensor – informs control units on pressure in the inlet pipeline (at the corresponding complete set);
- Sensors and TNVD regulators (built-in) - are used by control units at calculation and management of the moments and amount of the fuel injected into the engine;
- The coupling sensor - is used by control units when performing functions of a tempostat;
- The activation sensor switch To/in – informs control units on inclusion or switching off of the conditioner of air (at the corresponding complete set).
Basic installation of the moments of injection is made at installation of TNVD on the engine. In the course of functioning of the unit of change of this characteristic occurs automatically on the ECM teams by means of the cam executive mechanism.
The dosage of the fuel given to the engine is made by means of the valves of quantity and the moment of injection which are built in TNVD. Operation of valves happens according to the teams issued by the TNVD control unit which is usually located in the top part of the pump. On the main rotor of TNVD the special ring is established. The sensor of provision of a rotor defines situation and speed of rotation of a rotor. The sensor works by the principle similar to the principle of operation of the sensor of provision of a bent shaft. Four tags - according to the number of cylinders are applied on a rotor. The control unit of the pump obtains necessary information from the control unit of the engine (ECM) and counts the moments and duration of supply of fuel. The TNVD internal components allow to count very precisely these parameters that finally leads to increase in efficiency of return of the engine and decrease in toxicity of the fulfilled gases.
On diesel models there is no gas cable, - its functions are performed by the sensor of provision of a pedal of an accelerator. The sensor continuously informs the control unit on the provision of a pedal that allows ECM to count injection parameters precisely. Idling turns are also regulated by the control unit and are not subject to manual adjustment. Analyzing information arriving from various sensors, the control unit counts quantity of turns, correcting them depending on loading and temperature of the engine.
The pump connects to nozzles metal tubes. Each nozzle gives fuel to combustion chambers through five openings. It reaches uniform distribution of fuel in the combustion chamber and the exact direction of supply of fuel. The system of injection of fuel is system of direct injection. In the bottoms of pistons there are vortex cameras providing a turbulence of the fuel coming to combustion chambers. For optimization of combustion of fuel of a nozzle open in two stages (for this purpose in each nozzle there are two springs). When opening a nozzle a small part of fuel gets on internal components of a nozzle, greasing them, and comes back to the fuel tank.
Control of warming up of the cold engine is exercised of the control unit of the engine and the TNVD control unit. At the cold engine the moment of injection is displaced by the TNVD control unit. The control unit of the engine, in turn, operates work of candles of an incandescence. Glow plugs are installed in each cylinder and join before start of the engine, working during an engine provorachivaniye with a starter and some time after start of the engine. Candles considerably facilitate start of the cold engine. After inclusion of ignition on the control panel the control lamp (see the Head Governing bodies and methods of operation) signaling about inclusion of candles of an incandescence lights up. As soon as the lamp goes out, it is possible to start implementation of start of the engine. At very cold weather of a candle continue to work still some time after start of the engine, providing stability of functioning of the last and decrease in level of maintenance of toxic components in the fulfilled gases.
If from sensors information confirming emergence not of an emergency situation arrives, ECM switches in emergency operation of functioning when instead of inadequate signals basic values of the corresponding parameters are substituted, - efficiency of return of the engine in such mode, naturally decreases. Prevents operation of a control lamp of refusals on an instrument guard of the car about ECM entrance to emergency operation of the driver (see the Head Governing bodies and methods of operation at the beginning of the Management), in the processor memory at the same time the corresponding diagnostic code is brought (see the Head Sistemy of electric equipment of the engine).
Under certain circumstances the behavior of the car can not change at all. Increase in toxicity of the fulfilled gases can be the only sign that ECM passed into emergency operation of functioning.
Keep in mind that after replacement of the faulty sensor on serviceable automatic return of system will not switch independently in the normal mode does not occur, - it is necessary to clear the processor memory of the diagnostic codes which are contained in it. Even if the conducting break was the cause of transition of system to emergency operation of safe, after its processor memory it has to be cleared.
At operation of a control lamp the car follows at the first opportunity to drive away on company car repair shop Opel for performing detailed diagnostics with use of the special equipment and performance of necessary recovery repair.
The diagnostic equipment (the reader of skanerny type) is connected to the DLC socket located under a decorative slip under ahead lever of the parking brake.