Matching analysis of piston motion phase difference of an opposed-piston two-stroke gasoline engine

In order to achieve asymmetric scavenging, the piston motion phase difference between two pistons was designed for higher scavenging efficiency on an opposed-piston two-stroke (OPTS) gasoline direct injection (GDI) engine. Based on a numerical simulation of the piston dynamics, gas exchange and in-cylinder working process of an OPTS-GDI engine, the effect of piston motion phase difference on the scavenging process, mixture formation, combustion process and engine performance was investigated. The simulation results show that with the increase of piston motion phase difference, the scavenging efficiency and the flame development and rapid burning duration were increased gradually. The indicated work would be increased first and then decreased with a maximum value at 15° crank angle of phase difference. Cousidering the influence of phase difference on the scavenging and in-cylinder working process, the best piston motion phase difference was about 15° crank angle at 15 kW/6000 r/min of full load conditions.