Development of a Two-Stroke/Four-Stroke Switching Gasoline Engine - The 2/4SIGHT Concept

Abstract

<div class="htmlview paragraph">The pursuit of flexibility is a recurring theme in engine design and development. Engines that are able to switch between the two-stroke operating cycle and four-stroke operation promise a great leap in flexibility. Such 2S-4S engines could then continuously select the optimum operating mode - including HCCI/CAI combustion - for fuel efficiency, emissions or specific output. With recent developments in valvetrain technology, advanced boosting devices, direct fuel injection and engine control, the 2S-4S engine is an increasingly real prospect.</div> <div class="htmlview paragraph">The authors have undertaken a comprehensive feasibility study for 2S-4S gasoline engines. This study has encompassed concept and detailed design, design analysis, one-dimensional gas dynamics simulation, three-dimensional computational fluid dynamics, and vehicle simulation. The resulting 2/4SIGHT concept engine is a 1.04 <i>l</i> in-line three-cylinder engine producing 230 Nm and 85 kW.</div> <div class="htmlview paragraph">When simulated in the Ford Focus, a European C-class car, the powertrain recorded a fuel consumption of 5.93 <i>l</i>/100km over the NEDC drive-cycle, without the need to use lean combustion. This represents an improvement in fuel efficiency of 24% compared with the series production Focus vehicle equipped with an equivalent conventional gasoline engine.</div> <div class="htmlview paragraph">The project has been undertaken with funding from the UK Department of Trade and Industry, as part of the Foresight Vehicle initiative.</div>