On the design of slider-crank mechanisms. Part II: multi-phase path and function generation

Abstract

A method to design slider-crank mechanisms to achieve multi-phase path and function generation applications typically accomplished by adjustable planar four-bar mechanisms is presented. The benefit of this method is twofold. First, multiple phases of prescribed coupler curve points or crank and follower displacement angles are achievable using a mechanism with fewer moving parts than the planar four-bar mechanism. Second, the slider-crank mechanism can achieve these phases of prescribed values without any physical or automated adjustments of its moving pivots between phases. A slider path that enables the slider-crank to achieve two phases of prescribed coupler curve points or crank and follower displacement angles is designed by using seventh order polynomials to connect the moving pivot paths of the follower link of the adjustable planar four-bar mechanism. This polynomial generates smooth radial displacement, velocity, acceleration and jerk profiles with boundary conditions that can be prescribed. The example problems in this work considers a two-phase moving pivot adjustment of a planar four-bar mechanism.