Diesel Common Rail Technology
Find out more about the technology behind Common Rail Direct Injection Diesel Engine.
Common rail direct injection does away with traditional pump injectors and replaces them with a central storage 'rail' or tube, where the fuel is kept under extreme high pressure and then released via precise, electronically controlled solenoid injectors, directly into each cylinder.
This high pressure creates a fine mist of fuel for a more efficient burn, which leads to better fuel efficiency.
The system consists of 4 major components:
- A high pressure pump with pressure regulator and inlet metering valve.
- The 'rail' which contains a pressurised reserve of fuel.
- Injectors which inject precise amounts of fuel into the combustion chambers as required.
- A central processing unit (the Electronic diesel Control Unit - ECU) which controls injector flow and timing electronically, along with rail pressure, while continuously monitoring the operating conditions of the engine.
How it works
Step 1. Air Intake (Intake Stroke)
As the intake valve opens, air enters the engine's cylinder. For a turbocharged engine this air charge will be compressed (which increases the oxygen available for combustion) and forced into the cylinder.
Step 2. Pressure Builds (Compression Stroke)
After the intake valve has closed, the air charge is compressed further in the cylinder which increases its pressure and temperature. Towards the end of the compression stroke, fuel injection begins.
Step 3. Fuel Injection & Combustion (Power Stroke)
As fuel injection commences, the fuel and air mix together to form a combustible mixture. The high temperature in the cylinder causes the mixture to self ignite (without the need for a spark plug) a short time after injection begins. As the mixture burns, cylinder pressure rises rapidly and the piston is forced down the cylinder generating power.
Step 4. Exhaust (Exhaust Stroke)
The combustion process ends when the fuel air mixture has burned and released all of its energy. Towards the end of the expansion stroke the exhaust valve opens and the hot gases begin to escape from the cylinder. The piston moves up the cylinder to help push the waste product out of the cylinder. Energy from these hot gases is used to spin the turbocharger before being passed through the catalyst and particulate filter to minimise harmful tailpipe emissions.
Step 1. Air Intake (Intake Stroke)
As the intake valve opens, air enters the engine's cylinder. For a turbocharged engine this air charge will be compressed (which increases the oxygen available for combustion) and forced into the cylinder.
Step 2. Pressure Builds (Compression Stroke)
After the intake valve has closed, the air charge is compressed further in the cylinder which increases its pressure and temperature. Towards the end of the compression stroke, fuel injection begins.
Step 3. Fuel Injection & Combustion (Power Stroke)
As fuel injection commences, the fuel and air mix together to form a combustible mixture. The high temperature in the cylinder causes the mixture to self ignite (without the need for a spark plug) a short time after injection begins. As the mixture burns, cylinder pressure rises rapidly and the piston is forced down the cylinder generating power.
Step 4. Exhaust (Exhaust Stroke)
The combustion process ends when the fuel air mixture has burned and released all of its energy. Towards the end of the expansion stroke the exhaust valve opens and the hot gases begin to escape from the cylinder. The piston moves up the cylinder to help push the waste product out of the cylinder. Energy from these hot gases is used to spin the turbocharger before being passed through the catalyst and particulate filter to minimise harmful tailpipe emissions.
