Common Rail: everything you need to know about this technology

Common Rail: you have probably been hearing and/or reading about this term for a few years now, but today we are going to tell you everything you need to know about this technology. First, it is important to be clear about what it is: it works as a fuel injection system controlled by the engine control unit and is designed for diesel engines.

It is important to know that fuel injection takes place directly in the combustion chamber. The fuel, diesel, travels from the tank to the high-pressure pump, through the lines that lead to the injectors.

How does the Common Rail system work?

Fuel flows from the tank to the high-pressure pump; up to this point the system is low pressure. In some cases they use electric pumps inside the fuel tank.

The high-pressure pump is responsible for generating enough fuel pressure to guarantee a perfect spray inside the cylinder, facilitating the spontaneous ignition of the mixture.

Pressures can vary between 300 and 2,500 bar, depending on the engine’s load requirements. When the fuel leaves the high-pressure pump it passes through a series of common conduits, which is where the system gets its name, Common Rail, or rails, and then reaches the injectors. Once there, the injectors are electrically controlled by the vehicle’s engine control unit.

https://www.youtube.com/watch?v=bgcdSpxIVUc

What advantage does the Common Rail system have?

The main advantage of this technology is that it can be electronically controlled, which makes it possible to achieve pre-injections and post-injections. In this way, greater performance and a greater reduction in noise can be achieved.

For the Common Rail system and therefore the engine to work correctly, the sensors must be up to date. The most important ones? The crankshaft position sensor, the CMP sensor, the mass airflow meter, the accelerator pedal sensor, the injector rail pressure sensor and the turbo intake pressure sensor.

Once the sensors have received the information, the actuators are the ones that must carry out the command. The most important ones? The injectors, the solenoid valves for exhaust gases, better known as EGR, the intake throttle, the glow plug preheating, rail pressure and flow regulator.

In addition to this advantage, it is important to note that this technology makes fuel injection cleaner and much more efficient. This is possible thanks to the short spray distances and to multiple injection. Engines produce fewer emissions and are capable of delivering more power. Fuel consumption is also noticeably reduced. It is worth mentioning that it can be implemented in a wide variety of diesel vehicles since it is a modular system.

https://www.youtube.com/watch?v=y1KGy4Tzguo

More than 70% of diesel cars use the Common Rail system

This technology marked a before and after in terms of performance and efficiency. Bosch was one of the first manufacturers to develop it, in 1997.

According to Goodyear, “common rail is possibly the most efficient injection system fitted to diesel vehicles today. Its function is to move fuel from the tank to the injectors. It may seem obvious, but it is not as simple as it looks: the car’s performance and consumption depend on perfect timing at this stage of the powertrain.” “The Common Rail system has been in production lines for more than 20 years and is constantly being renewed“.

“Common Rail is one of the most efficient injection systems used in vehicles today, and its use has become standardized in recent years so that diesel cars offer ever better performance. Its advantages are well known to manufacturers, but the great beneficiaries of its use are drivers.”