The operation of the system is based on the regulation of the fuel supply depending on the speed of the crankshaft and the amount of intake air.
Fuel from the fuel tank is taken by the fuel pump and fed through the fuel filter to the injection pump, and then to the injectors (pic. 3-51).
Pic. 3-51. Diesel injection parts «1Z» and «AFN»:
1 - toothed pulley of the injection pump drive;
2 - key;
3 - injection pump;
4 - injection advance regulator;
5 - stop solenoid valve;
6 - bracket for fastening the high-pressure fuel pump;
7 - fuel injection pump cover;
8 — stop valve block and fuel supply timing valve;
9 - fuel supply timing valve;
10 - speed controller;
11 - high pressure fuel line;
12 - nozzle of the 3rd cylinder with a valve needle lift sensor;
13 - nozzle holder.
Electronic control unit (ECU) determines the amount of injected fuel and maintains the optimal composition of the combustible mixture, depending on:
- intake air and fuel temperatures:
- frequency of rotation and angular position of the engine crankshaft;
- coolant temperature;
- the position of the slider of the injection advance regulator;
- absolute pressure in the inlet pipeline;
- the amount of air taken in;
- position of the fuel control pedal.
Depending on the results of processing this information, the information block determines the amount of injected fuel and the moment of fuel supply and issues the appropriate control signals to the high-pressure fuel pump (pic. 3-52).
Pic. 3-52. diesel injection pump «1Z» and «AFN»:
1 - speed controller;
2 - drain fuel line;
3 - injection advance regulator;
4 - fuel supply timing valve.
The air path of the system is hermetically sealed, which excludes air leakage in addition to the air flow meter.
Starting a cold diesel engine Enrichment of the mixture during a cold start is provided by injectors. The degree of enrichment is determined by the ECU depending on the following parameters:
- coolant temperature;
- the duration of the starter;
- crankshaft speed. The operation of the system when the diesel engine is warming up.
The necessary enrichment of the mixture when the diesel engine is warming up is carried out according to the signals of the coolant temperature sensor. Depending on this information, the ECU increases the duration of fuel injection.
Diesel engine idling. The ECU receives the crankshaft speed signal from the speed sensor and the engine load signal from the pedal position sensor, and compares the received speed signal with the programmed value. If the number of revolutions differs from the programmed value. The ECU accordingly increases or decreases the current of the control signal issued to the speed controller, which adjusts the amount of fuel injected to obtain the desired engine operation.
According to the signals from the coolant temperature sensor, the ECU provides an increase in the crankshaft speed required when the diesel engine warms up.
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