Structural and Kinematic Features of Three-Link Centroid Mechanisms and Synthesis of Non-Circular Gears of a Planetary-Rotor Hydraulic Machine

Abstract

The development of modern technologies opens up new possibilities for the production and use of centroid mechanisms, including planetary-rotary hydraulic machines. The problem of profiling non-circular gears of such hydraulic machines has not yet received its final solution. Previously developed methods either did not provide an acceptable tooth shape or required increased clearances in the gearings. In this article, the problem of the mentioned above hydraulic machine design is solved on the basis of analysis of thethree-link centroid mechanismstructure general principles. Features of centroid mechanism design having round and non-circular gears are studied. The importance of the Aronhold-Kennedy and Willis theorems in the geometric synthesis of such mechanisms is emphasized. In relation to the synthesis of non-circular gears for a planetary mechanism with planetary gears, it was established that in this mechanism the transition motion of the satellites cannot be carried out at a constant angular velocity. An in-depth analysis of the issue made it possible to develop a more accurate method for designing the working mechanism of planetary-rotary hydraulic machines. This method includes thefollowing stages: choosing the parameters of the designed working mechanism prototype of the hydraulic machine - the original, calculated round-link planetary mechanism; choosing the calculated trajectories of the satellite center in coordinate systems connected with each of the central gears, which are described by a common cyclic function; calculating the angular positions of the satellite corresponding to various phases of its motion; calculating the correction for the satellite radial position, which specifies the profile of the epicycle teeth; graphical construction of non-circular gearprofiles as envelopes of the generating satellite. The new method ensures the absence of tooth interference and favorable conditions for transmitting motion in gearings. The method is quite simple and can be used by a wide range of calculation engineers based on national software systems.