Development through Simulation of a Turbocharged 2-Stroke G.D.I. Engine Focused on a Range-Extender Application

An original 2-stroke prototype engine, equipped with an electronically controlled gasoline direct-injection apparatus, has been tested over the last few years, and the performances of these tests have been compared with those obtained using a commercial crankcase-scavenged 2-stroke engine. Very satisfactory results have been obtained, as far as fuel consumption and unburned hydrocarbons in the exhaust gas are concerned. Large reductions in fuel consumption and in unburned hydrocarbons have been made possible, because the injection timing causes all the injected gasoline to remain in the combustion chamber, and thus to take part in the combustion process. Moreover, a force-feed lubrication system, like those usually exploited in mass-produced 4-stroke engines, has been employed, because of the presence of an external pump. In fact, it is no longer necessary to add oil to the gasoline in the engine, as the gasoline does not pass through the crankcase volume. The aim of this paper is to present the main features of a new 2-stroke engine, which mainly pertain to the adoption of a turbo compressor for the scavenging and supercharging processes, as well as a small volumetric impeller for the start transitory. Because of its limited size, weight and high specific power output, this engine should be of particular interest for range extender applications in electric vehicles. A numerical simulation has been carried out, to confirm results of the experimental phase, by means of a one-dimensional model that has furnished encouraging results.