Design and Analysis of Momentary-Dwell Mechanisms

Abstract

This paper presents a general theory for the dwell characteristics and for the synthesis of momentary-dwell mechanisms. Dwell conditions are obtained from the simultaneous solution of a set of equations derived recursively through the differentiations of a general form of displacement equation. A general synthesis approach is presented. It involves the use of analytical solutions of the lower-order dwell criteria as initial estimates and the development of a computer-aided procedure to subsequently readjust the mechanism proportions by heuristic optimization. The proportions thus obtained represent tradeoffs among higher orders of dwell and various prescribed kinematic and dynamic characteristics. For most practical purposes, such a solution is useful and acceptable. The coupler-dwell mechanism is used to illustrate the theory and approach. In particular, two mechanisms design problems are investigated. One deals with the kinematic synthesis of a six-bar coupler mechanism with shockless dwell and with prescribed unlimited crank rotations as well as optimum transmission; and the other concerns the design of a chain-linkage drive, including an analysis on the effect of the chain dynamics.