To the Choice of the Source of the Closing Power at Implementing the Fore Closure of Elements of the Planetary Continuously Adjustable Transmission

Abstract

Force closure is a widely used method of non-opening (permanent contact) of the working surfaces of higher kinematic pairs, along with the geometric closure. In a common mechanism with a higher kinematic pair - a gear train with a constant gear ratio - form-fitting is traditionally used with great success, which ensures in the most widespread involute gear both the constancy of the center distance and the presence of the necessary clearances (radial and lateral) in the meshing. At the same time, the implementation of its functional purpose does not create any prerequisites for the use of the force circuit of the elements. In a specific planetary continuously variable transmission, the implementation of the functional purpose (change in the gear ratio of the transmission) occurs as a result of the synchronous radial movement of the satellite and the sectors of the central gear wheel, accompanied by a change in the center distance. In this case, form-fitting of working surfaces can also be implemented, but this will require the creation of a complex mechanism. Force closure of the satellite and sectors of the central gear wheel provides a significant simplification of the transmission design, allowing, when changing the gear ratio of the gear, to communicate the control action to only one of its elements - the satellite or sectors of the central gear wheel. The inversion of their kinematic functions (fixing the satellite from rotation around its own axis and communicating the output movement to the central gear wheel) simultaneously develops a tendency to simplify the design of the transmission and dictates the need, firstly, to use a type of engagement that excludes double-profile contact, and, secondly, the use of an elastic element as a source of the closing force, which does not require connection with the environment to perform its function. If the replacement of the type of meshing in the planetary continuously variable transmission is not a problem, then the choice of the type and design of the elastic element for the force closure is a difficult task. The paper describes the influence of various types of elastic elements on the transmission design.