The Design Of A Speed Shifting Mechanism Based On Non-Circular Gear

At present, the usual transmissions are gear transmission, fluid transmission, electric transmission and ECVT. Gear transmission is the most commonly used speed shifting mechanism, but it has to be used with a clutch and cost more time. Another widely used speed shifting mechanism is auto gear train transmission, but it's often complicated in structure.Based on the theory and technique of the non-circular gear, a speed shifting mechanism with a structure of non-circular gear and a feature of non-stop is designed in this thesis. It has two main characteristics:firstly, it can shift speed unceasingly, so the mechanism efficiency is improved; secondly, it's not limited in one or two gear ratios, but can be used to get many gear ratios.Firstly, the basic concept, design theory and relevant technique of the non-circular gear are analyzed in this thesis. Then the design method of an elliptical gear is described, the design, modeling and kinematic simulation of a mechanism are completed based on the elliptical gear.Secondly, a lot of calculation and design of the speed shifting mechanism are completed, including the entire structure, pitch curve, driven gear teeth, transmission gear teeth, transition gear teeth, transmission ratio, gear teeth meshing and speed.Thirdly, by the Pro/Engineer software, the modeling and kinematic simulation of the speed shifting mechanism are completed. In terms of modeling, the mechanism model is created by lots of superior functions, like parametric definition, program and data sharing. The kinematic simulation is used for checking up the entire structure, the meshing of the gear teeth and the motion of the mechanism.Lastly, in the ADAMS environment, the dynamic simulation is completed. By defining the parameters of material, gravity, load and collision, the practicability of the mechanism is verified. With the comparison of the dynamic and kinematic results, the method to optimize the mechanism is analyzed.