Control of electronically controlled Common rail system

1. Adjusting the fuel injection pressure [common rail pressure]

Using a common rail pressure sensor to detect the fuel pressure of the common rail, thereby adjusting the fuel injection volume of the fuel supply pump and controlling the common rail pressure

2. Adjusting the fuel injection quantity

According to the engine speed sensor, accelerator pedal position sensor, the ECU calculates the most accurate fuel injection quantity, and directly controls the fuel injection quantity of the fuel injector by controlling the energization and power-off time of the fuel injector solenoid valve

3. Adjusting the fuel injection rate

According to the operating conditions of the engine, set and control the fuel injection rate to achieve pre injection, main injection, post injection, multi stage injection, etc. There are three injection modes for electronically controlled Common rail system:

〔1〕 Primary injection - In one working cycle of the engine, each cylinder injector has only one injection, that is, the main injection is applied to the early electronically controlled Common rail system.

〔2〕 Two injections - before the main injection, advance to a small amount of pre injection, namely pre injection+main injection. The purpose of pre injection is to significantly reduce combustion noise.

Attention point: Pre injection can cause an increase in PM emissions. Therefore, the pre injection should be as close as possible to the main injection.

〔3〕 Repeated injection - dividing the injection process in each working cycle into hypothetical dry stages, with each stage of injection being independent and independent of each other. Repeated injection generally includes multiple stages such as guided injection, pre injection, main injection, post injection, and secondary post injection.

The purpose of repeated injection is to control the combustion speed.

Attention point: During the repeated injection process, the injector solenoid valve must be opened and closed multiple times, resulting in high energy consumption.

4. Adjusting the injection time

Based on the engine speed and load, the ECU calculates the most accurate fuel injection time, and accurately controls the fuel injection time of the injector by controlling the energizing and power-off times of the injector solenoid valve.