Methodology for engine diagnosis

Fundamental investigations on malfunction diagnosis at marine diesel engines based on reconstructed in-cylinder pressure information

To fulfil the needs of marine Diesel engine customers, an engine diagnose tool was developed which provides precise information on the actual state of the engine on the basis of cylinder pressure measurements via the indicator cock. The investigation was elaborated in context of a master thesis at ETH Zurich and started with a one dimensional engine simulation model. The indicator cock´Â™s geometry was replicated regarding to simulate the distorted pressure at the end of the indicator path. In a next step models of common engine malfunctions were developed with the simulation software. The reconstructed in-cylinder pressure provides a basis for running the engine at the maximal designed cylinder pressure and a further thermo dynamical analysis enables malfunction diagnosis. The presented algorithms are implemented in an engine analysis system called THE DOCTOR DM 8-32 (Fuchs Technology Group) and shows a practical application of the method developed in the first part of the paper. The engine diagnose tool is represented as a light-weight computer, which can be taken on-board, comprises data gathering as well as post-processing and pressure trace interpretation.