Abstract
The opposed-piston, two-stroke (OP2S) engine was once widely used for ground, marine and aviation applications. Despite its record-setting combination of power density and fuel efficiency, historic opposed-piston engines suffered from high NOx and soot and poor oil control [1]. As a result, their use in on-highway applications eventually ceased with the introduction of global emissions standards.
This study’s objective was to demonstrate how modern technologies and engineering methods have been leveraged to develop an opposed-piston, light-duty engine that is clean and significantly more fuel efficient than today’s powertrains.
Included in the paper is a:
Short overview of the opposed-piston engine’s inherent thermodynamic advantages
Summary of the Achates Power engine’s performance and emissions results
Fuel economy and emissions comparison to a published light-duty benchmark, the Cummins 2.8L Advanced Technology Light Automotive Systems (ATLAS) diesel engine [2], designed to meet the fully phased-in Tier 3 or LEV III emissions requirements
Discussion of an exhaust temperature control strategy used to achieve the aggressive catalyst light-off requirements of light-duty applications
The results of this study demonstrate that the Achates Power OP2S—which has already proven its benefits for medium-duty applications [3]—also features efficiency, emissions, cost and weight advantages for light-duty applications. In fact, the advantages for light-duty vehicles are even greater than those previously demonstrated for commercial trucks [4].
KEYWORDS – opposed-piston engine, two-stroke engine, internal combustion engine, compression ignition engine, fuel-efficient engine