A Study On Elastic Meshing Effect Of Three-ring Gear Drives

The three-ring gear drive is a novel kind of internal planetary transmission withsmall tooth number difference. This kind of gear drive has some distinguishadvantages, such as large speed-reduction ratio, high load capability, compact volumeand simple structure, etc, which make the gear drive be used in many fields. When the three-ring gear drive is bearing rather heavy load, the actualcontact tooth number will exceed the theoretic contact tooth number calculatedby contact ratio. This phenomenon can be explained that in such a mechanism theclearances between working profiles of each non-contact tooth pair near theaction line are very small, and when the gears are applied of load, thedeformation of the contact tooth pair may be greater than the clearances, so thesenon-contact tooth pairs will come into contacting and share the total load. Thusthe bearing capacity of three-ring gear drive is increased by this phenomenon, whichmay be called Elastic Meshing Effect (EME). It is of great significance to carryout the study on EME of three-ring gear drive to increase the bearing capacity,minimize the volume and reduce the cost. On the basis of an analysis of theoretic clearances and teeth deformation, amathematic model was developed in this thesis to describe the state of multi-toothcontacting and load distribution, and a method was proposed to involve the EME ingear strength evaluation. For considering the influence of manufacturing errors, amethod of static strength evaluation was presented for the first time. The influence onEME of design parameters was investigated. Bearing capacity experiment was carriedout in order to verify the theoretic analysis. Considered the EME, a new set of three-ring gear drive model series, whosecentral distances and speed-reduction ratios were ranged by standard geometricalseries, was designed by the research team. The comparison between the new modeland the old revealed that the bearing capacity has been improved a lot.