Study On Nonlinear Dynamic Characteristics Of Helical Gear In Dual-clutch Transmission

With the advancement of technology and machinery industry, gear drive as an important form of mechanical transmission which is more widely used in engineering application. In the field of automobile, gear drive play an important part in transmission system, vibration and impact properties directly affect the performance of the car, so the engineering applications of the gear transmission system is put forward higher request. Through studying the characteristics of the vibration and noise, the meshing impact characteristics and transmission accuracy, understand the influence with structural parameters of the gear system, the processing method and the structure to the system dynamic behavior, so as to provide guidance for practical engineering application.This thesis based on the design of Dual Clutch Transmission (DCT) research project, focused on the helical gear transmission system as the research object, established the multi degree of freedom coupling equation, using the finite element method and numerical method, studied the inherent characteristics and dynamic response of the gear system, analyzed the nonlinear characteristics and the influence of parameters on the system’s dynamic characteristic, so as to provides the basis of further theoretical research and design of high-performance gear system. The dissertation consists of the following contents:(1) Analyzed the vibration of the helical gear system with theoretical foundation of gear system dynamics, studied parameters of the system, such as stiffness, damping and other parameters, and established a more realistic bend-torsion-axes-swing helical gear vibration model.(2) Using the numerical method and the finite element method (FEM) to study the inherent characteristics of helical gear system by contrast, obtain the inherent frequency and vibration model of the system, indicated the coupling vibration model is feasible.(3) Excitation factors of the helical gear system were studied, simulated the time-varying meshing stiffness excitation, error excitation and external excitation, taking into account the practical application of the nonlinear equation of backlash, bearing clearance, established the bend-torsion-axes-swing nonlinear coupling helical model.(4) Studied the nonlinear dynamic response with nonlinear coupling model by numerical method, and also discussed the speed, damping and stiffness parameters which influence the dynamic response of the system, obtained the time-domain diagram, phase diagram, Poincare map, system bifurcation diagram and frequency graph. Studied the multiple degree freedom of coupling model, and nonlinear behavior of multiple clearance system.Results of this thesis show that: multi-degree of freedom of helical gear on the theoretical study of feasibility, the system parameters and nonlinear factors which affect the system dynamic characteristics in different degrees of freedom; backlash increases, the vibration displacements are different in each degree of freedom; the low speed region, the system vibration is unstable, easy to appear chaotic state; support stiffness decreases, system vibration amplitude increase obviously.