Technology Decoded: Common Rail Direct Injection (CRDi)

Common Rail Direct Injection is a very effective technology for diesel engines as it leads to better fuel efficiency, less vibrations and noise, reduced emission levels and many other technical improvements. As the name indicates, CRDi involves just one fuel rail and pump for all the cylinders rather than separate pumps and fuel rails for each cylinder as is the case in conventional diesel engines. It is also known as DICOR/CRDe etc. Different brands or OEMs use a particular name for this technology with slight innovations and enhancements.

Background/Development: 

• Robert Huber developed the first prototype of common rail system in the 1960's.
• Dr. Marco Ganser further developed the technology for next level.
• The first successful usage in a production vehicle began in Japan by the mid-1990s.

Technology Explained: 

The main components of CRDi are: 

• High Pressure Fuel Pump
• Common Fuel Rail /Accumulator that runs alongside cylinder head, and is maintained at very high pressure
• Electrically operated injectors that are under the control of Electronic Diesel Control (EDC) unit. Let us have a look at other insights below:

1. Fuel is first drawn by electric pump from fuel tank and is then forwarded to the high pressure fuel pump that is driven by the engine itself. This pump delivers highly pressurized fuel into the “COMMON RAIL” that acts as a reservoir/accumulator for highly pressurized fuel. Fuel from this common rail is supplied to each fuel injector through delivery lines.

2. The pressure of the fuel in the common rail is dependent on engine speed because fuel pump is driven by engine itself. Thus, more the speed of engine, more the fuel is pressurized by the pump.

3. Various sensors like pressure sensor, throttle position sensor, crank position sensor, fuel temperature sensor etc. govern the proper functioning of CRDi system. Based on inputs received from these various sensors, ECU decides right amount and timing of fuel to be injected through each injector and executes it with the help of on-board EDC unit.

Watch this video for better understanding of CRDi:

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