Performance assessment of a novel mechanism design of spark- ignition internal combustion engine

Abstract

ABSTRACT In this study, the performance of an internal combustion engine with a novel and recently patented mechanism design is studied. The novel mechanism uses a rack and pinion assembly connected to a crank rocker four-bar mechanism instead of the connecting rod. This new design eliminates all the negative friction loss effects of the side-thrust load and the piston slap problems encountered in existing conventional internal combustion engines. The novelty of the patented engine design is in the elimination of the connecting rod and wrist pin used in conventional slider-crank mechanisms. The new mechanism design improves the performance of the engine and removes significant sources of noise accompanied by conventional slider-crank mechanisms. A mathematical model including kinematics and thermodynamics analysis is presented. A simulation code using MATLAB® is developed to obtain the performance curves of the engine with a new design including a pressure-volume diagram, work, and piston velocity. It was found that the new novel engine design produces about 27% higher work per cycle than the conventional engine with identical dimensions, which means that the thermal efficiency is raised by 27%. Furthermore, the new design provides a unique motion profile that decreases the ignition delay time and therefore allows more time for the entire air-fuel mixture to be burned.