The Application Research Of Airsprings For New Generation Low-speed Maglev

Airspring is an important component of secondary suspension for new generation low speed maglev,the effects of whose dynamic characteristics on the dynamics performance of maglev should be drawn much attention on.A nonlinear model for airspring and a dynamics model for new generation low speed maglev are established in this thesis,and the dynamic characteristics of airspring have been analyzed.A co-simulation is performed with these two models to analyze the effect of the modelling approaches and physical parameters of airspring on the dynamics performance of low speed maglev.According to the above work,some conclusions can be reached.Among the frequency ranging from 0 to 20Hz,the vertical stiffness of airspring would not vary with the frequency in the range of low frequency.For high frequency the vertical stiffness increases with increasing frequency.And larger orifice diameter will decrease the vertical stiffness and the increase of ratio between auxiliary chamber volume and main chamber volume Vr/Va and excitation amplitude will result in the increase of the stiffness.When the orifice diameter is small,the displacement ratio peak will decrease as the orifice diameter increases.While the orifice diameter is greater than a certain value,the displacement ratio peak will start to increase as the orifice diameter increases and the eigenfrequency will move to a lower one.The displacement ratio peak and eigenfrequency will both decrease as Vr/Va increases.And a larger excitation amplitude will lead to a vsmaller displacement ratio peak.As the co-simulation result,it is shown that the vertical ride quality index computed by the nonlinear model is greater than the one by linear model when vehicle is running on the tangent track,and the maximum roll angle of carbody and the horizontal displacement of aispring to the contrary when vehicle is passing curves.The vertical ride quality index significantly varies with the orifice diameter.Only when the value of orifice diameter is proper,the carbody can reach a good ride quality.The orifice diameter has little influence on curve negotiating performance of maglev vehicle.Better vertical ride quality can be reached as the Vr/Va increases.When vehicle is passing curves,the maximum roll angle of carbody and maximum vertical and horizontal displacement of airspring will increase as the Vr/Va increases,while the maximum longitudinal displacement to the contrary.When the vehicle is passing large-radius curves in any superelevation condition,the variation of vertical displacement of airsprings in the same bogie will possess symmetry,which means the amount of compression on the one side is equal to the amount of stretch on the other side.At the same time,the three airsprings on the same side of vehicle will show the consistency of vertical displacement.When vehicle is passing curves in the cant deficiency and cant excess condition,the amplitude of vertical displacement of airspring occurs on the circle curve section.While the amplitude appears on the transition section when vehicle passing curve in the balance condition.There is no symmetry and consistency of vertical displacement of airspring when vehicle is passing small-radius curves.