Research On Characteristics Of Variable Damping Anti-yaw Damper For High-speed EMU

With the development of Chinese railway network,railway lines have more strict requirements for the dynamic performance of EMUs.High-speed EMUs usually operate on exclusive high-speed railways,but the existing railway lines account for a large proportion in China's railway network.Due to the limitation of topography,some small radius curves are unavoidable,and there are a lot of small radius curves on some special railway lines.Therefore,the safety can not be ignored on curved track.The anti-yaw damper is installed between the car body and the bogie frame,which produces resistance to prevent rotational vibration and controls the hunting of the bogie,but also hinders the rotation of the car body relative to the bogie on curved track.In order to take into account the hunting stability and the safety on curved track,it is usually necessary to compromise the damping characteristic parameters of anti-yaw damper.According to the actual structure of anti-yaw damper and the working principle of damping valve system,a single-direction anti-yaw damper model is established in AMESIM software.The effects of oil density,oil viscosity,diameter of normally-on orifice,stiffness and preload of spring on the damping characteristics are analyzed.The damping characteristics of the damper are determined by the diameter of the normally-on orifice when the vibration speed of the damper is relatively low.After the corresponding damping valve is opened,the stiffness of spring affects the damping coefficient.And the pre-load of spring affects the speed when the corresponding damping valve is opened.Based on the actual parameters of EMU trailer,the vehicle system dynamics simulation model is established in SIMPACK software.The vehicle dynamic performance evaluation indexes are determined according to GB/T 5599-1985 and 95 J 01-M.The influence of unloading speed and damping force of anti-yaw damper on dynamic performance is analyzed.The results show that the critical speed of hunting stability increases with the decrease of unloading speed and the increase of damping force.The damping characteristics of anti-yaw dampers have a significant influence on the evaluation indexes of lateral dynamic performance,but have little influence on vertical dynamic performance.In terms of the evaluation indexes of lateral dynamic performance,the unloading speed and damping force of anti-yaw damper have different optimal values.In this paper,the damping characteristic curve is optimized by adding the optimization point before the anti-yaw damper unloading.The speed of the optimization point is determined by the 2 ? principle,and the damping coefficient of the optimization point is selected by the influence of the damping characteristics on the dynamic performance.Finally,six simplified optimization curves of the damping characteristics are determined.The effects of different simplified optimization curves on dynamic performance are compared and analyzed,and the optimal optimization curve is determined after comprehensive consideration.The diameter of normally-on orifice,the pre-load force and stiffness of supplemental damping valve,the pre-load force of pressure regulator valve and the pre-load force of safety valve are optimized in turn to obtain an actual damping characteristic curve which is almost identical to the simplified optimization curve.Finally,the influence of the actual damping characteristics of the original anti-yaw damper and the anti-yaw damper with optimized structural parameters on the vehicle dynamic performance is compared and analyzed.It is found that the optimized anti-yaw damper have a better balance between the passing performance of small radius curve lines and operation stability.