COMMON RAIL DIRECT INJECTION (CRDI / DICOR / CR4 / CRDE) is one of the latest engine technologies in the diesel domain. This blog will attempt to understand its functioning and importance for everybody's benefit.
Indirect Injection is characterized by moderate Torque output, moderate Power Output, lesser Noise level and Direct Injection is characterized by Better Torque Output, Better Power Output and more Noise. Taking the better things from both the technologies, CRDI has been developed. So it can be said to possess the following characteristics:
- Fully electronic control system – Fuel quantity & Injection timing controlled by ECU
- Injection opening period controlled – No delivery setting or pump timing
- Multiple injections per cycle
- Fast response injections
- Very High Pressures (upto 1600 bar)
- Fault detection
Noise is a result of rapid pressure increase inside the cylinder. Hence multiple injections are provided to ease the pressure and reduce the noise levels.Injection of a Small amount of fuel in to the combustion chamber during the pilot injection phase initiates pre-combustion. This produces a slight increase in the compression pressure which shortens the ignition delay of the main fuel charge.
Why is high pressure reqd? This is to ensure precise injection of fuel thus controlling fuel quantity and emission.
The following sensors help the ECM / ECU to take more informed decision on fuel quantity and timing:
- Crank Angle sensor
- Cam Phase sensor
- Rail Pressure sensor
- Fuel Temperature sensor
- Air mass flow sensor
- Boost Pressure sensor
- Accelerator pedal position sensor
- Knock sensor
- Coolant temperature sensor
- Atmospheric pressure sensor
- Vehicle speed sensor
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