5.2. Fuel system of diesel engines
Two systems of injection of diesel fuel are used. The 1.9 liters engines are equipped with the semi-electronic Bosch AS3 system, and engines 2.1 liters are equipped with a full control system of the Lucas EPIC engine (the electronic programmed injection control).
The system of injection Bosch provides electronic control of the fuel pump of high pressure and the choice of time of injection, and also operates action of system of repeated combustion of exhaust gases (EGR) and glow plugs.
The system is run by the electronic control device (ECU) which receives signals from the sensors controlling engine loading, frequency of rotation of the engine, work of nozzles and temperature of cooling liquid. The ECU control unit through a cable of an accelerator and a vacuum diaphragm defines timepoint of injection of the fuel pump and operation of the electromagnetic EGR valve.
The system of injection Lucas EPIC provides the programmed electronic control of the fuel pump of high pressure and electronic control of system of repeated combustion of exhaust gases via the block of electronic control (ECU).
The system is run by the control ECU device from sensors of provision of a pedal of an accelerator, depression in an inlet collector, turns of the engine and position of the crankshaft, temperature of cooling liquid and temperature of the soaked-up air. Operation of the EGR valve is also operated by ECU in combination with the electromagnetic valve.
Unique feature of this system – management of an accelerator. Instead of a cable of the accelerator connected to the pump of high pressure, the pedal of an accelerator is connected with the sensor of provision of a pedal. This sensor sends signals of provision of a pedal of ECU which, in turn operates the fuel pump of high pressure by means of electronics.
The fuel system includes:
– the fuel tank installed in a back part of the car;
– the fuel filter with a separator;
– the fuel pump of high pressure adjusted by means of electronics;
– the connecting components.
Before passing of fuel via the filter fuel heats up the cooling liquid passing through the basis of the fuel filter. The turbocharger and the refrigerator are established on all models.
Fuel from the fuel tank to the fuel pump of high pressure moves the centrifugal pump located in the fuel pump of high pressure. In front of the fuel pump the fuel filter where purification of fuel of foreign debris and water is made is installed. Surplus of fuel greases the fuel pump and on the pipeline comes back to the fuel tank.
The fuel pump of high pressure rotates with a speed twice smaller, than the crankshaft, and is put in action by a gear belt from the crankshaft.
The amount of the given fuel is run by the centrifugal regulator which reacts to the provision of a pedal of management of supply of fuel and frequency of rotation of the engine. The regulator is connected with the measurement valve which increases or reduces amount of the fuel given for each cycle of operation of the pump.
The moment of injection of fuel is defined by the pump. During the operation of the engine the moment of injection of fuel changes automatically in the pump from the ECU system.
Four fuel nozzles spray fuel in the vortex cameras located in a head of the block of cylinders. Nozzles are calibrated in such a way that open and closed with strictly certain pressure that provides effective and full combustion of fuel. Each needle of an injector is greased with fuel which collects in space about a spring, and then arrives to a returnable hose.
Start of the cold engine is facilitated due to existence of the candles of an incandescence installed in each vortex camera. On the Bosch system the speed of idling of the cold engine increases at the expense of the vacuum influencing through a diaphragm an accelerator cable. On the Lucas system the mode of idling is automatically regulated by the fuel pump. On both systems management is made by the ECU block.
The electromagnetic valve of a stop of the engine blocks supply of fuel to a rotor of the fuel pump at switching off of ignition. On the fuel pump of high pressure Bosch there is also an engine stop lever.
The fuel pump at good service can work before repair more, than the engine. The main reason for damage of the fuel pump and nozzles – dirt or water in fuel.
Service of the fuel pump and nozzles are very difficult. Therefore it needs to be made at the Peugeot station.
At work on system of injection Lucas it is necessary to observe additional precautionary measures:
– always disconnect the negative plug of the accumulator before shutdown of any of sockets of fuel system;
– at installation of the accumulator do not mix a pole;
– do not subject system components (especially ECU) to blows;
– do not open the ECU block;
– exclude hit of moisture in components of system of electronic control (at a wash of the engine protect system from water hit).