Atkinson cycle: a way to improve efficiency in internal combustion engines

Abstract

Expanded cycles, like the one developed by Atkinson for internal combustion engines (ICM), are used to make better use of fuel and increase thermal efficiency. In this paper, the Watt’s and Stephenson’s kinematic structures is presented from the point of view of the mechanics of machinery and graphs theory, which by means of multi-link arrangements, allow recreating the mechanism presented by James Atkinson. By applying a kinematical analysis to these kinematic structures, the problems related to the piston speeds and accelerations that prevent the massive introduction of the “classical Atkinson cycle” in automotive engines are revealed. Despite this fact, the Atkinson cycle is highlighted in this work as a real promising constructive technology, given the advances in electronic hardware and control technologies.