The Basic Principles of Common Rail Electronic Fuel Injection Technology for Diesel Engines

The Basic Principles of Common Rail Electronic Fuel Injection Technology for Diesel Engines

Electronic fuel injection technology has evolved from initial position-controlled to time-controlled systems, and common rail electronic fuel injection technology belongs to the latter. The common rail electronic control system uses various relevant sensors to collect and transmit diesel engine operating status parameters to the control unit (ECU). The ECU calculates the injection quantity, injection pressure, injection timing, and injection rate based on the target setpoints, and then issues commands to the actuators to drive their actions, allowing the diesel engine to operate in its optimal state.

Common rail electronic fuel injection technology refers to a fuel supply method that completely separates the generation of injection pressure and the injection process from each other in a closed-loop system composed of a high-pressure fuel pump, pressure sensor, and electronic control unit (BCU). It uses a high-pressure fuel pump to deliver high-pressure fuel to the common fuel line, achieving precise control through the fuel pressure within the common fuel line. This makes the high-pressure fuel line pressure independent of engine speed, significantly reducing the degree to which the diesel engine's fuel supply pressure varies with engine speed, thus mitigating the shortcomings of traditional diesel engines. The ECU controls the fuel injection quantity of the injectors, which depends on the fuel rail pressure and the opening time of the solenoid valve.

This technology departs from the traditional plunger pump's pulsating fuel supply principle. Instead, it directly or indirectly generates a constant high-pressure fuel supply via the common rail, distributing it to each injector. By utilizing the opening and closing of a high-speed solenoid valve integrated on each injector, the amount of fuel injected into the diesel engine's combustion chamber is controlled in a precise and timed manner. This ensures the diesel engine achieves optimal combustion ratios, good atomization, optimal ignition timing, sufficient energy, and minimal emissions.

Common rail electronic fuel injection technology for diesel engines integrates computer control technology, modern sensor detection technology, and advanced injector structure. It not only achieves high injection pressure and controls injection pressure and quantity but also enables pre-injection and post-injection, thereby optimizing injection characteristics, reducing diesel engine noise, and significantly reducing exhaust emissions.