Bosch introduced the Common Rail Injection System for passenger car DI-Diesel engines in June 1997 for series production. Bosch is currently working on a fairly high number of follow-up projects with customers around the world.
The major differences of Common Rail System compared to standard Diesel injection equipment are the free choice of the injection pressure and timing as well as the benefit of the now available pilot injection at almost all operating points.
The objective of the CR-System is to reduce the combustion noise significantly, and to improve the torque curve, especially in the lower engine speed range. Simultaneously, the emissions must be kept in the first step within the limits posted by the European legislation for the year 2000.
This paper presents combustion related application experience as well as the advantages to the customer in terms of torque, power, fuel economy and noise. The effects of EGR on the timing and quantity of the pilot injection with respect to combustion noise and smoke is presented. Also included are the Common Rail System-specific demands on the nozzle as a crucial component of the system.
It is believed that the emission results achieved and the possibility of meeting even stricter emission standards shows the potential of the Common Rail System.