Reduction of Exhaust Gas Emission in a Two-Stroke Engine with Pneumatic Fuel Injection

In this article possibilities of fuel injection control in two-stroke engines are presented. This is a low cost in-cylinder fuel injection system for stratified charge engines according to idea of Professor Stanislaw Jarnuszkiewicz with modified system of gases movement organization, that is much simpler than alternatives. The authors modified this pneumatic fuel injection system by means of hot exhaust gases drawn from one cylinder during the working stroke and, following the addition of fuel, forced into another cylinder during the compression stroke. Spraying and injection of fuel by means of hot exhaust gases give additional possibilities of complete evaporation of light fuels, alternative fuels with extended fraction and heavier fuels, such as diesel oil, kerosene and vegetable oil. In the combustion system presented the process of preparing liquid hydrocarbon fuel for combustion is one of the main factors influencing the efficiency of the conversion of chemical energy contained in the fuel to mechanical energy. The most significant is the fuel phase transition, and especially a repeatability of the fuel dose per cycle. This process is inseparably associated with the physical properties of fuel, and changes of rate of pressure in gas duct. In practice, a two-stroke internal combustion engine with spark ignition and pneumatic injection accomplished by means of exhaust gases successfully uses liquid fuels with very different fractional and group composition, which may be very beneficial from the viewpoint of practical realization of utilization processes. The results of tests shown it is possible to reach a high repeatability of the fuel dose per cycle and maintaining uniform fuel doses for each cylinder.