Research On Dynamic Characteristics Of Gear Transmission System In A Heavy-Haul Locomotive

Gear transmission is a vital component for power transmission,and it has been widely employed in machinery,aerospace,shipbuilding,rail transit and other fields,due to its many advantages such as high efficiency,compact structure,reliable operation and long service life.The particularity of the operating environment for rail vehicle makes the locomotive gear transmission suffer not only the dynamic excitation from the gear transmission,but also the external wheel-rail interface disturbance.With the rapid development of railway locomotives in the direction of high speed,heavy load and high power density,the dynamic responses of the locomotive system caused by the nonlinear dynamic excitation of the gear transmission and the nonlinear disturbance of the wheel-rail interface become more and more intensified,which results in dynamics problems such as vibration and noise,or even the fatigue failure of power transmission components,so that the dynamic performance and service life of the locomotive system will be affected seriously,and the reliability and safety issues will arise.However,investigations on the dynamic performance of locomotive gear transmission are relatively rare at home and abroad,and it is still in the initial research stage.Therefore,it is urgent to carry out the related research work on the dynamic characteristics and changing laws of the heavy-haul locomotive gear transmission system under the combined action of complex internal and external dynamic excitation.In view of this,a locomotive-track coupled spatial dynamics model considering dynamic effect of the gear transmission system is established in this thesis,so as to reveal the coupling effect between the heavy-haul locomotive gear transmission system and the locomotive-track system,and the nonlinear coupled vibration mechanism between the gear transmission system and the wheel-rail contact.By using this model,the influence rules of the traction motor suspension parameters on the dynamic characteristics of the gear transmission are analyzed.And the dynamic characteristics of the gear transmission are studied under the combined actions of the typical wheel-rail excitation and the time-varying mesh stiffness excitation.The outcomes of this thesis have important theoretical significance and engineering application value for the dynamic characteristics evaluation of the gear transmission system in the vehicle vibration environment,the optimization design of the gear transmission parameters,and the operation and maintenance of the locomotive and the railway line.The main research work includes:(1)Based on the vehicle-track coupled dynamics theory and the gear dynamics theory,a comprehensive locomotive-track coupled spatial dynamics model considering dynamic effect of the gear transmission is established,which mainly includes three subsystems,namely a locomotive subsystem,a track subsystem and a gear transmission subsystem.The dynamics equations of the entire system model are derived in detail.(2)The dynamics simulation program of locomotive-track coupled system considering the dynamic effect of the gear transmission system is developed.The new fast explicit integration method(ZHAI method)is adopted to numerically solve the equiations of the locomotive–track coupled dynamics system.The simulated results and the field test results of the locomotive during acceleration process are compared and analyzed from the perspective of time and time-frequency domains.The established dynamics model is validated by the fine agreement between the simulated and the tested results.(3)The dynamic response of the system under the combined action of the gear time-varying mesh stiffness and the track irregularity is analyzed.The effects of dynamic effects of gear transmission on different locomotive dynamics indicators and vibration response of the key components in the locomotive,and the vibration response of the rail are studied.The coupling mechanism between the gear transmission system and the locomotive-track system is revealed.(4)The dynamic responses of the gear transmission systems are analyzed under the conditions with different suspension parameters such as the vertical stiffness of the motor suspension,the radial stiffness of the axle bearing,the longitudinal and the lateral suspension distances of the boom.The influence of different motor suspension parameters on the dynamic characteristics of locomotive gear transmission system is studied,which would provide certain theoretical guidance for the selection and optimization of the design parameters of the locomotive gear transmission.(5)The dynamic characteristics of the gear transmission under the combined action of complex wheel-rail disturbance(wheel polygon,rail weld)and the gear time-varying mesh stiffness excitation are studied.The locomotive and its drive system under different wheel polygon and rail weld parameters are analyzed respectively.The influence law and safety limit of the dynamic characteristics of the locomotive transmission system under the impact of wheel polygon and rail weld are obtained.The research results could provide a theoretical reference for the locomotive manipulation,operation and maintenance.