Injection sequences that include periods both pre and post the main injection can be utilized to reduce emissions, particularly NOx enabling the system to meet the stringent emissions levels required by EURO-III and US–98 legislation and beyond.
The inclusion of pilot injection results in a significant reduction in engine noise.
Full electronic control
The common rail offers all the benefits of full electronic control for vehicles, including extremely accurate fuel metering and timing, as well as the option to interface with other vehicle functions. The common rail can be easily adapted for different engines. The main components are as follows.
- Common pressure accumulator (the ‘Rail’).
- High-pressure regulator.
- High-pressure supply pump.
- Electronic solenoids.
- Electronic Control Unit.
- Filter unit.
hows the layout of a common rail injection system. The system consists of a common pressure accumulator, called the ‘rail’, which is mounted along the engine block, and fed by a high-pressure pump. The pressure level of the rail is electronically regulated by a combination of metering on the supply pump and fuel discharge by a high-pressure regulator.
The pressure accumulator operates independently of engine speed or load so that high injection pressure can be produced at low speeds if required. A series of injectors is connected to the rail, and each injector is opened and closed by a solenoid, driven by the Electronic Control Unit. A feed pump delivers the fuel through a filter unit to the high-pressure pump. The high-pressure pump delivers fuel to the high-pressure rail. The injectors inject fuel into the combustion chamber when the solenoid valve is actuated.
The compact design of the injector outline enables the LDCR system to be used on 2 or 4 valves per cylinder engine.
With one electronically driven injector per engine cylinder, the system is modular and can be used on 3, 4, 5, and 6-cylinder engines.
Low drive torque
As the pumping of the pressure rail is not phased with the injection, the common rail system requires a low drive torque from the engine.
Independent injection pressure
The injection pressure is independent of the engine speed and load, so enabling high injection pressures at low speed if required.
Because the injection pressure is independent of engine speed and load, the actual start of injection, the injection pressure, and the duration of injection can be freely chosen from a wide range. The introduction of pilot injection, which is adjusted depending on engine needs, results in significant engine noise reduction, together with a reduction in NO x emissions. The actuator controls the pressure in the system.
0%, and the emission of carbon monoxide, nitrogen oxide, and hydrocarbons by at least 95%. Diesel engines are also powerful; turbocharged automotive diesel engines are already capable of maximum
specific torque levels of 170 Nm, and specific power ratings of more than 60 kW/liter of cylinder capacity. At the same time, the fuel consumption of diesel engines is very low. Diesel is the yardstick against which all other propulsion systems are measured in this respect.