Determining common rail system tolerances using Monte Carlo Method and Design-of-Experiments

ABSTRACT Common rail systems provide fuel at a defined rate, pressure and time. These parameters vary from system to system, injector to injector, shot to shot due to component and subcomponent tolerances. A precise forecast of these tolerances can pose a challenge especially in the presence of learning functions that are designed to improve system accuracy. Rail pressure peaks are a consequence of confined control accuracy. They impose durability requirements upon affected components like rail, injector and pump. The tolerance calculation scheme described in this paper is based on the well-known Monte Carlo Method (MCM). The software function considered is implemented into the algorithm as Matlab code. In order to provide a mathematical description of the high pressure pump and its fuel metering unit a data-based model has been created, based on Design-of-Experiments measurements. This analysis allows to consider a large number of influence parameters. This article contains a detailed description of the calculation scheme as well as the applied tools. A comparison of the system performance with and without the supporting software function concludes the investigation.