Free-piston diesel engine timing and control - toward electronic cam- and crankshaft

The free-piston diesel engine replaces the crankshaft of the traditional diesel engine with a power turbine to convert energy from the exhaust gas. Hence, the pistons move freely in the cylinder, mainly influenced by pressure and friction forces. Instead, the motion of the pistons are controlled by an electronic control system - an electronic crankshaft. In addition, the camshaft is replaced by an electronic timing system that triggers and actuates the motion of the valves - an electronic camshaft. In this paper, we describe a hierarchical multirate electronic control system developed for an experimental engine, focusing on piston motion parameter estimation, valve and injector timing, and a piston motion control system. Experimental results with a full scale experimental test engine are included. The results show the effectiveness of the developed control strategy