Structural Synthesis and Geometry Analysis of Planetary Intermittent Motion Mechanisms with Elliptical Gears

摘要

Mechanisms with intermittent movement of the output link are widely used in drives of automatic and semiautomatic machines. Currently, the most widespread are the mechanisms of a permanent structure with one-way coupling (ratchet, anchor mechanisms) and mechanisms of a variable structure (Maltese mechanisms, star mechanisms, incomplete gears), however, they are characterized by high loads on the links due to impacts that occur at the beginning or end of the phase movement. The aim of this work is the structural synthesis of actuators, in which the rotational motion of the input link is converted into intermittent motion of the output link, while the kinematic chain does not open during the cycle of the mechanism. As a synthesis method, a structural mathematical model is used in the form of a system of equations that describes the relationship between the quantitative and qualitative composition of the links and kinematic pairs of the future mechanism, its mobility, the number of connections to the rack and other structural parameters. Based on the results of structural synthesis, planetary gear schemes with elliptical gears are constructed, which, with certain gear sizes, allow intermittent motion of the output shaft. A geometric analysis of the mechanisms with elliptical gears is carried out, as a result of which the principle of their action is shown, link position plans are constructed and the output shaft rotation angle functions are obtained. Since the motion with stops is carried out without breaking the kinematic chain, the developed mechanisms are more reliable and compact in comparison with existing analogues, and can be recommended for wide practical application. Possible structural designs of the synthesized mechanisms and examples of use as part of a conveyor and mixer drive with intermittent movement of the impeller are shown.