Research On Friction Vibration Transmission Path And Fault Diagnosis Of Compound Planetary Gearbox

The compound planetary gear transmission system has been widely used in more and more mechanical equipment,playing a huge role in the fields of vehicles and aviation and other fields.It’s quality greatly affects the healthy life and operation cost of the equipment.Under the condition of heavy load operation of gears,gear faults such as wear and scuffing will evolve,and the vibration excitation generated by these faults will react to the system through each transmission path,aggravate the wear rate of the system and affect the operation of the equipment.Therefore,it is necessary to carry out fault diagnosis and condition monitoring of the compound planetary gearbox,identify the transmission path caused by internal excitation,and improve the dependability of the equipment.The major research contents of this work are listed as follows.(1)Taking the compound planetary gearbox as the research target,the geometric model of the healthy gear pair and the scuffing model of the external planetary gear tooth surface were established,and the calculation formula of the meshing stiffness of the gear was derived.Considering the time-varying meshing stiffness,tooth side clearance and damping,the dynamic model of the compound planetary gear transmission system was established,and the influence of different degrees of gear scuffing fault on the vibration response of the system was analyzed.(2)The classical vibration transfer path analysis method,the vibration transfer path analysis method based on working conditions and the vibration transfer path analysis method based on power flow were studied.The contribution percentage of all vibration transfer paths caused by the scuffing fault of the planetary gear of the compound planetary gearbox was calculated theoretically.The influence of different degrees of faults on the vibration response of the system was analyzed.(3)The processing of the scuffing fault of the planetary gear was carried out,and the health status monitoring test scheme for gears with normal tooth surfaces and with different degrees of scuffing fault were designed.(4)Based on the unique structure of the compound planetary gearbox,all vibration transmission paths were analyzed and studied.The finite element method was used to simulate the power transmission evolution state of the system vibration transmission path caused by the scuffing fault of the external planetary gear of the gearbox,and then the vibration transmission contribution of each path was calculated.Finally,the main transmission path of the fault vibration signal was determined.This study can further provide a theoretical basis for component optimization on the main transmission path of vibration.