Development of power transmission system is more competitive than ever before. In order to keep competitive, powertrain manufacturers must optimize attributes, such as performance, cost, weight, durability and NVH while a new product is developed. For gear transmission, the challenge is the troublesome problem in the inherent mechanical components of a transmission system, including other power train elements like engine torque input and accompanying fluctuations. If the gear shapes are perfect, then the gear tooth meshing is better, therefore the gears will transmit the input torque in a more efficient manner without the generation of high frequency sounds from engine fluctuation.
In order to optimize the performance of gear transmission system, gear tooth modification(micro-geometry modification) is one of the most popular approach. Micro-geometry modifications include the intentional removal of material from the gear teeth flanks, so that the shape is no longer a perfect involute. Such modifications compensate teeth deflections under load, and the resulting transmission error is minimized under a specific torque. Therefore, the micro-geometry modifications can be applied on the involute (or profile) and lead of the gear teeth.
In this thesis, in order to do study on tooth micro-geometry optimization, a mass produced planetary gear type drive reducer was selected as prototype. The original design was modeled by a commercial software named Romax Designer which can analyze and optimize kinds of gear power transmission system. A serious analysis results were obtained that have some problem want to modify. Based on the result, optimization and gear tooth modification were done to deal with the load distributions on gear tooth, gear durability problem, safety factor and bearing life problem. As the results, after such optimization, outstanding performance improvement was presented in this thesis.