Numerical Analysis and Modeling of a Three Stroke IC Engine

Vinicius Vinhaes¹; Claudio Barberato¹

¹ Centro Universitario da FEI

doi:10.20906/CPS/COB-2015-1085

Resumo

A three-stroke internal combustion engine is a proposed engine which completes a complete combustion cycle of exhaust, intake, compression and expansion within a single revolution of a crankshaft. In this engine two pistons are housed in a single cylinder. The first piston is a common piston-connecting rod-crankshaft assembly, and it is responsible for the compression and expansion parts of the cycle. The second piston is a much lighter assembly and it is driven by means of rocker arm which follows a cardioids path milled in the crankshaft. The second piston is responsible for the exhaust and intake part of the cycle. This paper presents key parts of a three stroke engine modeled through Computer Aided Design (CAD) and studied numerically using Computer Aided Engineering (CAE). The purpose of the analyses is to assist the building of a prototype of such engine which, if shown feasible, will present several benefits when compared to the conventional four stroke engines, such as better power to weight ratio and higher fuel efficiency. A commercial computer aided design software was applied for building the models and a commercial computer aided engineering software was applied to the numerical analysis. Only the parts of this engine which differentiate them from a conventional four stroke engine, namely the connecting rod and the rocker arm, were studied. The two moments during the cycle which have the highest stresses were selected for each component, respectively, the maximum pressure inside the cylinder and the maximum acceleration for lighter piston. For simplicity, both scenarios were studied as static cases, because they lessen the inherited difficulties of designing and simulating complex energy systems such as an engine. The numerical analyses for both connecting rod and rocker arm show that the maximum deformations for the applied loads were within expected. The results show that the proposed components can cope with the maximum stresses found in a conventional engine and therefore the next stages of the d

Palavras-chave: Engine; 3D Modeling; Structural Analysis