MULTIMEDIA COURSEWARE ON MECHANISMS WITH CYCLOIDAL GEOMETRY

Cycloids are curves traced by a point on a circle that rolls on a straight line or another circle. The latter category is often referred as trochoids. Mechanisms with cycloidal geometry include cams, gears, gear trains, rotary engines, and Roots blowers.  Cycloidal gears, whose teeth have cycloidal profiles, are now almost obsolete, replaced by involute gears because of manufacturing costs. The Wankel engine, with its cycloidal rotor and chamber, has leakage problems and has not gained wide acceptance. Cams with cycloidal displacement are being replaced by those with polynomial function displacement. Consequently, most textbooks in kinematics do not cover these topics or cover them with limited scopes. Students and practicing engineers therefore do not have adequate exposures of these subjects.  With new ways of gear manufacturing like injection molding, cycloidal gears are reemerged as an option. Additionally, cycloidal gears could also play an important role in the emerging field in Micro ElectroMechanical Systems (MEMS). 1 Moreover, there is a renewed interest 2 in the Wankel engine for hybrid vehicles with hydrogen fuel.  To help students understand and visualize the motion of these mechanisms, the author has developed courseware on cycloidal gears, cams, and other mechanisms, with simulation files generated from MATLAB, Working Model 2D, and visualNastran 4D.  All curves addressed in this paper are generated with MATLAB, and each MATLAB file can also generate animated simulation. Working Model 2D files, based on the geometry calculated from these MATLAB files, help students visualize the motion of these cycloidal mechanisms. The simulation files are hyperlinked with text files containing background information and cycloidal equations.