The system operates by regulating the fuel supply depending on the crankshaft speed and the amount of air intake.
Fuel from the fuel tank is taken by the fuel pump and fed through the fuel filter to the high-pressure fuel pump and then to the injectors (Fig. 3-51).
Fig. 3-51. Details of the diesel injection system "1Z" and "AFN":
1 — toothed pulley of the fuel injection pump drive;
2 — key;
3 — Fuel injection pump;
4 — injection advance regulator;
5 - electromagnetic stop valve;
6 — fuel injection pump mounting bracket;
7 — fuel injection pump cover;
8 — block of the stop valve and the fuel supply moment valve;
9 — fuel supply timing valve;
10 — speed controller;
11 — high pressure fuel line;
12 — 3rd cylinder injector with valve needle lift sensor;
13 — nozzle holder.
The electronic control unit (ECU) determines the amount of fuel injected and maintains the optimal composition of the combustible mixture depending on:
- intake air and fuel temperatures:
- rotation frequency and angular position of the engine crankshaft;
- coolant temperature;
- injection advance regulator slider positions;
- absolute pressure in the intake manifold;
- amount of air intake;
- position of the fuel pedal.
Depending on the results of processing this information, the information unit determines the amount of fuel injected and the moment of fuel delivery and issues the corresponding control signals to the high-pressure fuel pump (Fig. 3-52).
Fig. 3-52. Fuel injection pump for diesel engines "1Z" and "AFN":
1 - speed controller;
2 - fuel drain line;
3 — injection advance regulator;
4 — fuel supply timing valve.
The air tract of the system is sealed, which eliminates the possibility of air being sucked in other than by the air flow meter.
Starting a cold diesel engine The enrichment of the mixture during a cold start is provided by the injectors. The degree of enrichment is determined by the ECU depending on the following parameters:
- coolant temperature;
- starter duty cycle;
- crankshaft speed. Operation of the system during diesel engine warm-up.
The necessary enrichment of the mixture during diesel engine warm-up is carried out according to the signals from the coolant temperature sensor. Depending on this information, the ECU increases the duration of fuel injection.
Diesel engine idling. The ECU receives a crankshaft speed signal from the speed sensor and an engine load signal from the accelerator pedal position sensor and compares the received speed signal with the programmed value. If the speed differs from the programmed value, the ECU accordingly increases or decreases the control signal current sent to the speed controller, which adjusts the amount of fuel injected to obtain the required engine operating mode.
Based on signals from the coolant temperature sensor, the ECU ensures an increase in the crankshaft speed, which is necessary when warming up the diesel engine.
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