Dynamics Study Of The Primary Hydro-Pneumatically Interconnected Anti-Roll Device For High-Speed Train With Inside Axle-Box

Compared with traditional outside axle-box bogie,inside axle-box bogie has the advantages of light weight,compact structure and low wheel-rail interaction forces,etc.,which can achieve the purpose of lightweight design,energy conservation and pollution reduction.It is an important development direction of the next-generation high-speed train in China.In this thesis,the primary hydro-pneumatically interconnected anti-roll device with cross-connecting pipelines is proposed to solve the critical primary anti-roll problem of trains with inside axlebox,so as to improve the anti-roll and anti-overturning performance of high-speed trains with inside axle-box.According to the structure and working principle of the device,a nonlinear physical parameter model is established,and the static and dynamic characteristics of the device are simulated by MATLAB/Simulink.A SIMPACK-MATLAB/Simulink co-simulation model is established to analyze the effect of the device on high-speed train’s dynamic properties.The specific researches are as follows:(1)The dynamic model of a 400 km/h high-speed train with inside axle-box is established by using SIMPACK software.In consideration that the stiffness of anti-roll torsion bar is not changed,primary suspension’s parameters are optimized or additional primary anti-roll devices are installed to ensure that vehicles don’t roll at large angle when running on the line.The effect of primary vertical stiffness and damping,primary anti-roll stiffness and damping on dynamic properties,and the effect of primary anti-roll stiffness on crosswind safety and flexibility coefficient of vehicles running on large-radius curves and small-radius curves are analyzed by simulation.Based on the results,increasing primary vertical stiffness can significantly reduce roll angles.Primary anti-roll stiffness has little effect on ride quality,but can effectively control the rolling motion.The maximum crosswind velocity that the vehicle is allowed to withstand raises significantly with the increase of primary anti-roll stiffness.In order to meet the gauge requirement that the flexibility coefficient of vehicle is smaller than0.28,primary anti-roll stiffness should be bigger than 0.28 MN·m/rad in unloaded-car condition and 1.13 MN·m/rad in loaded-car condition.(2)Considering the mass of the piston body,the state of oil in chamber,the friction force of the piston body,the pipeline flow model,and the judgment of chamber vacuum,a mathematical model of the primary hydro-pneumatically interconnected anti-roll device is established.Three models are used to simulate oil flow in pipelines,namely the ideal laminar flow model,the fluid mass vibration model and the Zielke transient model.The fluid mass vibration model is divided into two types: constant friction coefficient and variable friction coefficient.(3)The effect of the structural parameters and initial state of the primary hydropneumatically interconnected anti-roll device on static characteristics is analyzed.The equivalent rolling stiffness raises significantly with the increase of piston radius,and decreases rapidly with the increase of piston rod radius.The equivalent vertical stiffness and equivalent rolling stiffness decrease as the initial volume of airbag increases.The vertical static load has significant effects on the equivalent stiffness.The heavier load the device carries,the better anti-roll performance it has.(4)The effect of the diameter and length of connecting pipelines of the primary hydropneumatically interconnected anti-roll device on the dynamic characteristics is analyzed.The diameter and length of pipelines have significant effects on the dynamic characteristics when excitation frequency is lower than 20 Hz.The dynamic stiffness will be close to the static stiffness when excitation frequency is lower than 1 Hz.The dynamic stiffness will reach rubber joint’s stiffness,when excitation frequency is higher than 30 Hz.As the diameter of pipelines is bigger than 5 mm and the length of pipelines is smaller than 4 m,negative stiffness occurs at some excitation frequencies around 10 Hz.The dynamic damping first increases and then decreases with excitation frequency,and reaches a peak value at a certain frequency in the range of 5 to 20 Hz.The peak value frequency raises with the increase of pipelines’ diameter and the decrease of pipelines’ length.(5)The effect of the primary hydro-pneumatically interconnected anti-roll device on vehicle dynamic properties and vibration transmission is studied.The results show that the device can reduce the roll angle of vehicle and lateral ride quality index,and slightly make vertical ride quality index and comfort index bigger.The device can apparently increase the vibration transmissibility of vertical acceleration as excitation frequency is higher than 34 Hz,and the vibration transmissibility of rolling acceleration as excitation frequency is higher than16.8 Hz.