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This paper discusses research activities at the Technische Universität München on the HCCI combustion process, focusing on the development of a model-based control concept with pressure indication. As a first step sensitivity analyses have been carried out to investigate influences of different injection strategies on the combustion and emission characteristics. An optimal injection strategy has been determined and reasonable control variables and ranges corresponding to this strategy were defined. Comprehensive steady-state measurements have been conducted to detect the engine characteristics. In order to limit the experimental effort, principles of DoE (Design of Experiments) have been used to define a methodological approach in the planning of the measurements. Afterwards a multiple-input multiple-output engine model including boundary models for input settings has been designed out of the measurement results.

This SAE Technical Paper will give a summary of the detailed results of crank-angle-resolved friction measurements which were carried out in motored and pressureless operation on a floating liner single cylinder test engine with a displacement of 0.5 liters. Friction forces that occur during running-in are introduced and discussed with regard to mixed friction and hydrodynamic friction for different oil control rings. Three different ring pre-loads are examined using constant geometries. In a second test series, the outer contour and coating is varied while the pre-load stays constant.