1.What is EFI diesel engine

An electronically controlled diesel engine( for genset power in thailand) is an electronically controlled diesel engine that controls fuel injection and emissions. The EFI diesel injection system consists of a sensor, an ECU (computer) and an actuator. Its task is to electronically control the fuel injection system to achieve real-time control of the fuel injection quantity and fuel injection timing with operating conditions. Using speed, fuel injection time, intake air temperature, intake air pressure, fuel temperature, cooling water temperature and other sensors, the real-time detected parameters are input into the computer (ECU) at the same time, and the stored set parameter values or parameter map (MAP map) ) For comparison, after processing and calculation, the instruction is sent to the actuator according to the good value or the calculated target value. The actuator controls the fuel injection amount (solenoid valve closing duration) and injection timing (timing control valve opening and closing or solenoid valve closing start point) according to the ECU instruction, and simultaneously controls the exhaust gas recirculation valve, glow plug and other actuators In order to make the diesel engine running condition is good.

2.The difference between EFI and ESC

In terms of speed regulation, EFI and ESC belong to the category of electronic speed regulation, which is different from the mechanical speed control method. However, there is an essential difference between the fuel injection control method and the speed control control execution method, which can be compared in the following aspects:

2.1 Fuel injection pressure

The ESC injects diesel directly into the cylinder through a traditional high-pressure pump. Its injection pressure is limited by the pressure valve on the injector. When the fuel pressure in the high-pressure fuel pipe reaches the set value of the pressure valve, the valve is directly injected into the cylinder. Inside, the pressure of the pressure valve affected by mechanical manufacturing cannot be very large.

The electric injection machine first generates high-pressure oil in the high-pressure oil chamber of the injector by a high-pressure oil pump. The fuel injection of the injector is controlled by a solenoid valve. When fuel injection is needed, the electronic control system controls the solenoid valve to open and inject the high-pressure oil into the cylinder. The pressure of high-pressure oil is not affected by the pressure valve and can be increased a lot. The diesel injection pressure is increased from 100MPa to 180MPa. Such a high injection pressure can significantly improve the quality of diesel( for hoe to mount wrartsila diesel engin generator) and air mixing, shorten the ignition delay period, make combustion faster and more thorough, and control the combustion temperature, thereby reducing exhaust emissions.

2.2 Independent injection pressure control

The injection pressure of the high pressure oil pump fuel supply system of the ESC is related to the speed load of the diesel engine generator on cruise ship. This characteristic is detrimental to fuel economy and emissions at low speeds and part load conditions. The fuel injection system of the EFI engine has an injection pressure control capability that does not depend on the speed and load. You can choose the appropriate injection pressure to make the injection duration and ignition delay period better, so that the diesel engine's exhaust emissions under various operating conditions are low and economical. high quality.

2.3 Independent fuel injection timing control

The high-pressure pump of the ESC is driven by the camshaft of the engine, and its injection timing directly depends on the rotation angle of the camshaft. After a machine is adjusted, its injection timing is fixed and the injection timing of the EFI machine is completely The solenoid valve is controlled by the electronic control system to adjust. Instead of relying on the injection timing control ability of the machine to rotate, it is a key measure to achieve a good balance between fuel consumption and emissions. Experts have studied for many years and found that different injection times under different load conditions are required to produce optimal s efficiency.

2.4 Fast oil cut-off capability

The fuel must be cut off quickly at the end of the injection. If the fuel cannot be cut off quickly, the diesel injected at low pressure will emit black smoke due to insufficient combustion and increase HC emissions. The high-speed solenoid on-off valve used in the EFI diesel injector is easy to achieve quick oil cut. The high-pressure oil pump of the ESC cannot do this.

2.5 Execution mode of speed control

The electric governor is a governor that feedbacks the speed signal of the machine through a speed sensor. The governor compares the preset speed value and converts the difference into a governor signal to drive the actuator to control the oil supply rack or sliding sleeve. To achieve speed regulation, the fuel supply signal simply depends on the speed signal, and the adjustment of the fuel supply amount is achieved by the mechanical action of the actuator. EFI uses sensors such as speed, injection timing, intake air temperature, intake air pressure, fuel temperature, and cooling water temperature to input the parameters detected in real time into the computer (ECU), and the stored parameter values or parameters. The map (MAP map) is compared, and after processing and calculation, the instruction is sent to the actuator (solenoid valve) according to the good value or the calculated target value.