Method for turbocharging and supercharging 2-stroke engines, applied to an opposed-piston new concept for hybrid powertrains

Abstract

The internal combustion engine's (ICE) electrification calls to question ICE concepts nowadays, leading to new engine architectures conceived to operate as series hybrids. This is the case of the unit analyzed in this work; a 2-stroke, spark-ignited, rod-less opposed-piston engine (2S-ROPE). Previous results revealed some efficiency and maximum power drawbacks, which motivated the development of the supercharged or turbocharged engine version. Supercharging the engine results in a straightforward task; however, turbocharging the engine reveals serious stability problems due to the thermo-fluid-dynamic coupling between the intake and exhaust lines.This work presents a method to study and identify the exhaust line geometry since the impact of pressure pulse propagation on the scavenging process is one of the most critical points to be considered from the very first steps. Finally, despite the difficulties of turbocharging the presented 2S engine, the parametric study revealed a suitable geometrical configuration and the engine operative range. Compared to the supercharged engine version, the turbocharged one presents more difficulties but diminishes the mechanical compressor power consumption, implying an advantage in efficiency terms.