Design, manufacturing and testing of a prototype two-stroke engine with rhombic drive mechanism

Abstract

In this study, reciprocating motion of the piston in a single-cylinder, two-stroke, spark-ignition engine was achieved with a novel rhombic drive mechanism to reduce friction losses, vibration and the lateral forces of the piston on the cylinder compared to conventional engine with slider-crank mechanism. Three-dimensional model of the prototype two-stroke engine with rhombic drive mechanism was prepared in Solidworks software according to kinematic relations, and 3D assembly strength analysis was carried out with inertia relief method in Abaqus and Hypermesh software. According to the finite element model, the most critical component was determined as gear pins and endurance limit for the mechanism was satisfied. Then, the prototype of the single-cylinder, two-stroke, and spark-ignition engine with rhombic drive mechanism was manufactured. The engine was tested at different engine speeds from 1700 to 3000 rpm at stoichiometric air/fuel ratio. In the tests, performance characteristics of the engine and CO, HC, NO and CO2 emissions were obtained. Prototype rhombic-driven engine provided 0.98 Nm output torque at 2400 rpm and 0.3 kW output power at 3000 rpm. Maximum thermal efficiency was obtained as 23.55%. In total, about 11% weight reduction was achieved when compared with a mass-production engine with the same swept volume and compression ratio. This engine is expected to stand for an alternative range extender engine to use on light/unmanned aviation vehicles and small size agricultural applications.