Research On Coupled Fault Transfer Characteristics Of Planetary Gear Transmission Systems

Aiming at the problem that the fault signals of wind turbine gear transmission system is complex,weak,and difficult to identify,the fault characteristics under different fault condition are summarized starting from the internal dynamic excitations of gear box and vibration responses on the surface of the gear box.The transmission characteristics of fault excitation and the joint influence relationship between different meshes are found out through the transfer characteristic analysis,which provided the theoretical basis for fault diagnosis of multi-stage gear system with planetary gear transmission.The three-dimensional rigid-flexible coupling system model of the experiment platform under normal state,fixed axis gear crack fault state,planetary gear tooth missing fault state,planetary gear wear fault state,fixed axis gear root crack-planetary gear tooth missing coupling fault state and fixed axis gear root crack-planetary gear wear coupling fault state are established with the wind turbine fault simulation platform as the research object.The meshing contact force signals of each gear pair inside the gearbox is obtained through dynamic simulation;the fault characteristics of the internal excitation signals of multi-stage gear system under 3 kinds of single faults and 2 kinds of coupling faults conditions are obtained,which guided the fault diagnosis for the gearbox surface vibration signals measured by experiment.The vibration signal of gearbox surface is complex under fault condition,and the failure characteristics of the same fault at different measuring points have differences,which is related to the change caused by different vibration signal transfer path from the inside to the outside of gearbox.According to system identification theory and method,transfer function model of different signal paths is obtained,by taking the dynamic simulation gear meshing contact force signals inside the gearbox as input signal,and taking the measured vibration responses on the gearbox surface as output signal.Transfer characteristics of the system under normal and different fault conditions are analyzed.And the joint relation between corresponding paths and the transfer characteristics of joint fault in the process of contact force signal transferring to the gearbox surface response point are found out based on the composition,amplitude variation and contribution of each transfer path,which contributed to the fault characteristics identification of the single faults and coupling faults of multi-stage gear transmission system.