Research On The Stability Of Couplers With Friction Arc Surfaces Of Slave Control Locomotives For 20,000-Tonne Distributed Power Train

Since the 20,000-tonne heavy-haul train was introduced in succession,train accidents caused by lateral instability of couplers have occurred frequently,which pose a serious threat to the operation safety of heavy-haul trains.To reduce the risk of couplers’ lateral instability,measures should be taken to improve the capacity of couplers’ stability,which is essential to ensure the running safety of heavy haul trains.In this thesis,the influence of couplers’ parameters and secondary suspension parameters of the heavy-haul locomotive on the coupler stability are studied based on the simulation and experiment.The suggestion values for these parameters are proposed to provide the theoretical support for improving the couplers’ stability.In this thesis,the structural characteristics of the heavy-haul locomotive and coupler with friction arc surface are described,respectively.A simulation model of the 20,000-tonne heavy haul train is established in the multi-body system dynamics software SIMPACK.The accuracy of the model is verified by comparing the coupler behaviors(coupler forces and rotation angles)with testing results.The longitudinal in-train forces endured by the slave locomotive are analyzed based on the simulation and test data.The wheel/rail dynamic performance indexes are selected to evaluate the running safety.The results show that the model can simulate the dynamic performance of the slave control locomotive and coupler/draft gear system.Based on the established heavy haul train model,the influence of key parameters of the coupler on the compressive stability are studied,including the lateral deviation of the coupler box,friction coefficient,and the radii difference of the coupler end.To improve the lateral stability of the locomotive,the influence of the secondary lateral stiffness and the secondary lateral stopper is studied,especially the matching scheme of the free clearance and elastic stiffness of the secondary lateral stopper is analyzed.For the slave locomotive presented in this thesis,the results show that when the lateral deviation of the coupler box has a relatively large error,the coupler stability capacity is attenuated.The lateral deviation should be strictly controlled and should not exceed 4 mm.Increasing the friction coefficient can improve the coupler stability capacity during braking.The radii difference of the coupler end also has an important influence on the coupler stability.With the same radii difference,the larger the arc surface of the coupler end is,the higher the coupler stability is.Besides,decreasing the radius of the front draft stop is effective as well.For the secondary suspension parameters,increasing lateral stiffness plays a positive role in the coupler stability capacity.For instance,when the secondary lateral stiffness is increased to0.6265 MN/m,the coupler remains stable under the simulation conditions in this thesis.The free clearances of the secondary lateral stopper are too large,the secondary lateral stopper is challenging to restrain the coupler instability.The practical measure is to decrease the free clearance and adjust the elastic stiffness appropriately.Three optimization schemes are proposed based on static analysis and dynamic simulation.The maximum coupler angles are3.73 °,4.38 °,and 5.63 °,respectively,and they are decreased by 63%,57%,and 44%,respectively,comparing with the original design.Therefore,the optimization schemes can effectively improve coupler compressed capacity and limit car body lateral instability behavior,the effect of optimization program 1 is better than that of optimization program 2 and optimization program 3.