Experiment on the ignition performances of a free-piston diesel engine alternator

The free-piston engine alternator (FPEA) is an unconventional engine. The initialization of the new engine differs from the conventional engine due to the feature that it eliminates the crankshaft and flywheel system. This study performed an experiment to analyze the ignition characteristics of a compression ignited diesel FPEA. Meanwhile, the effects of injection position and starting force on the ignition were also investigated. The experimental result shows that the larger starting force does not absolutely bring about higher ignition efficiency for the initialization of FPEA, although it brings in a greater possibility for the engine to gain a higher compression ratio from its resonant reciprocation. The large, but inappropriate starting force may lead to a serious incomplete combustion for the ignition, and the level of combustion completion of ignition is influenced by the injection triggering advance position (ITAP). The experiment suggests that properly enlarging the ITAP can enhance the combustion efficiency of the ignition and is beneficial to enlarge the compression ratio of opposite cylinder, but an excessive ITAP may advance the injection and ignition cycle and further induce a misfire for the FPEA.