Contents: Diesel fuel injection system with…⤓ High pressure fuel pump (HPFP) ⤓ Operating principle of the fuel…⤓ Fuel temperature sensor ⤓ Fuel inlet flow control valve for…⤓ Fuel tank ⤓ Design features ⤓
The fuel supply system consists of the following main components:
- fuel injectors;
- high pressure fuel pump;
- high pressure fuel manifold;
- fuel tank;
- fuel filter.
General characteristics of the fuel system
| Fuel tank capacity, l | 75 |
| Fuel pump type | Double plunger fuel pump |
| Fuel filter type | Filter with replaceable filter element |
| Fuel injector type | With electromagnetic drive |
Layout diagram of the fuel system elements in a vehicle
Block diagram of the fuel supply and injection system
Diesel fuel injection system with high-pressure common rail fuel rail
The main distinguishing feature of the Common Rail system is the presence of a storage tank - a high-pressure fuel manifold (hereinafter referred to as HPFM), into which fuel is supplied under high pressure (usually from 20 to 180 MPa). From the HPFM, fuel is supplied to the injectors. The injector valve opens due to the energy of the fuel pressure. The valve opening mechanism is designed in such a way that when a control pulse is applied to the electromagnet installed in the injector, the control valve opens. Opening this valve causes fluid to flow in the injector channels. The resulting pressure difference causes the injector valve needle to rise.
Pulse signals with the required pulse duration are sent from the electronic engine control unit (hereinafter referred to as ECU) to the injectors. The amount of fuel supplied by the injectors depends on the pulse duration and the pressure in the HPTC.
The fuel pressure pumped into the HPFC is maintained by a valve regulating the fuel supply to the HPFC input, which operates on a signal from the ECM. generates a signal to regulate the pressure in the HPFC based on information coming from the HPFC fuel pressure sensor. If the pressure exceeds the maximum permissible value, the limiting valve bypasses the excess fuel into the return line.
Electronic injection control allows flexible regulation of the fuel combustion process, changing the injection parameters by changing the corresponding program in the ECU. In this way, it is possible to change not only the duration and moment of injection, but also the number of "portions" of injected fuel.
High pressure fuel pump (HPFP)
Fuel lift pump: supplies fuel from the fuel tank through the fuel filter to the injection pump,
Fuel pump regulating valve: bypasses excess fuel into the return line if the pressure in the section between the fuel pump and the fuel inlet flow regulation valve of the high-pressure fuel pump exceeds the set value.
Fuel inlet flow control valve of the high-pressure fuel pump: regulates the amount of fuel supplied (via the high-pressure fuel pump) to the high-pressure fuel pump based on signals received from the ECU.
Piston: having a constant stroke, creates high pressure.
Check valve for fuel supply at the outlet of the high-pressure fuel pump: prevents the occurrence of a reverse flow of fuel from the high-pressure fuel pump to the high-pressure fuel pump.
Check valve at the inlet to the high-pressure fuel pump: prevents the occurrence of a reverse flow of fuel from the high-pressure chamber to the low-pressure fuel circuit of the high-pressure fuel pump.
(The article was taken from the website: «www.MitsubishiMan.ru»)
Operating principle of the fuel injection pump
The camshaft is driven by a toothed belt from the crankshaft and drives the rotor of the fuel pump, as well as the cam that pushes the high-pressure pistons.
The pistons, driven by a cam, move in high-pressure chambers. Depending on the position of the inlet and outlet valves and the direction of movement of the pistons in the chambers, fuel is alternately sucked in and pumped into the feed line to the HPTC.
Figure M2 2.173 shows the sequence of operating strokes of each of the injection pump cylinders.
The ECU controls the correspondence between the current flowing through the winding of the electromagnetic valve regulating the amount of fuel at the inlet of the high-pressure fuel pump and the amount of fuel pumped into the high-pressure fuel pump. The control is carried out using the data from the pressure sensor in the high-pressure fuel pump. Based on the results of comparing the actual data with the array of control data, the ECU generates a control action.
Fuel temperature sensor
The fuel temperature sensor is located on the high-pressure fuel pump. The temperature is determined by the change in resistance of the sensor.
This sensor is a positive temperature coefficient thermistor.
Fuel inlet flow control valve for high pressure fuel pump
The degree of opening of the valve depends on the so-called duty cycle of the control signal pulses. In other words: the longer the pulse lasts within the repetition period, the greater the degree of opening of the valve.
The valve is located on the fuel injection pump.
Fuel tank
The fuel tank consists of the following components:
- fuel tank capacity;
- receiving and measuring unit;
- fuel supply line;
- return fuel line.
The receiving and measuring unit includes the following components:
- fuel level sensor;
- fuel filter (immersed in the tank);
- fuel pipes.
Design features
To improve safety in the event of an accident, the fuel tank is located in front of the rear axle of the vehicle.
The fuel tank design includes a valve that cuts off the fuel when the vehicle turns over.
For environmental reasons, no materials containing lead or hexavalent chromium are used in the production of the fuel tank.