Schematic of Common Rail Direct Injection

Schematic of the Common Rail Direct Injection System, a widely used technology in modern diesel (and some types of gasoline) engines to increase combustion efficiency and reduce pollution.

Here's a description of the components and flow of the system in step order:

1. Low-Pressure Side

• Submerged In-Tank Fuel Pump: A gas station immersed in the fuel tank, acting to suck the oil forward to the system.

• Fuel Filter: The oil flows through the fuel filter to trap dirt and separate the water before entering the high pressure pump because the common rail system is very sensitive to contaminants.

• Low-Pressure Supply: Low Pressure Oil Passage Hose Connecting Between Fuel Tank To Front Pump

2. High-Pressure Side

• High-Pressure Fuel Pump: The main heart of the system compresses oil to a huge pressure (pictured as high as 2,000 bar)

• Metal Fuel Rail: High-pressure oil is stored in a "common rail." This is like a pressure pot waiting for injection into the combustion chamber.

• Pressure Sensor: The pressure sensor on the rail will send a signal back to the ECU box to control the pressure in the rail to stabilize and suit the engine cycle.

3. Injection Control

• ECU (Electronic Control Unit): The engine's mechanical brain receives data from various sensors and processes it to command Fuel Injectors.

• Fuel Injectors: Solenoid or Piezo controlled electric nozzle, can be turned on-off very quickly

• Multiple Injections per cycle: In one ignition cycle, the system can order multiple oil injections (such as pilot, main injection, and follow injection) to make soft combustion, reduce noise, and reduce black smoke.

4. Return Line

• Note the orange / red line with the arrow pointing back: the excess oil from the pressure generation at the pump, and the excess oil from the nozzle, are returned to the oil tank, to cool and keep the pressure in the system balanced.

Summary of the highlights of this system:

1. Very high pressure: Allows fine atomization of oil to mingle well with air, burn completely.

2.Freestanding oil supply: The oil pressure is not based on the engine cycle like the old-fashioned system, but is controlled entirely electronically.

3. Economy and force: Provide good torque while using less fuel and cleaner exhaust emissions, sir.