Control of spark ignition IC engines operating on alternative fuel mixtures

Abstract

Authors consider propane widely spread in Russian Federation for low cost and for reducing emissions of harmful substances in exhaust gases. To deal with its main limitations: reduction in engine power and torque when used in gas phase, it is proposed to add portions of gasoline to propane. As parameters of this mixture differs from gasoline or propane alone, paper presents control method that includes IC engine process model, algorithms to set control parameters (ignition and fuel systems) and approach to decrease knock occurrence probability. In-cylinder pressure peak position is used as a criterion of optimality for ignition timing calculation, and algorithm of propane/gasoline ratio variation allows keeping optimal spark advance as long as possible and preventing knock. The control method proposed is confirmed by test runs on MAHA LPS 3000 dyno stand. Experiments showed increase of engine power and torque. Knock, emissions and fuel cost were decreased.