Research On Effect Of Train Air Spring On Vehicle System Stability

The vehicle vibration problem is increasingly outstanding especially in the high-speed train operation,along with the rapid development of rail transit in our country.Vibration characteristics of railway vehicles is related to the quality of the vehicle running.At the same time,the vibration is also an important source of fatigue and the subjective discomfort of human.Therefore,it is necessary to seek better vehicle vibration reduction measures for improving the problems caused by vehicle vibration.The combinative way of practical test and theoretical simulation are adapted for current research.The bigger factors of vehicle vibration can be find through analysis.The vehicle will get better dynamic property through the reasonable improvement.It considers introducing the equivalent mechanical model of air spring to secondary suspension in the traditional rail vehicles model.A improved model of vertical vibration of vehicle system is established containing Nishimura air spring.According to Lagrange method the system vibration differential equation is deduced and then into matrix form.Which provides the basis for the random vibration of vehicle system simulation analysis.Based on the basic theory of random vibration,using track random irregularities as the systematic incentive.Vehicle system dynamics response of the parts are simulated by adopting the combination of time domain and frequency domain analysis method.In the time domain,the time course response of vehicle system is obtained by using fourth order Runge-Kutta method through C language program.The corresponding spectrum diagram is obtained after FFT processing.The influence of different air spring parameters on vehicle time response are analyzed.The study found that air spring effective area have a greater influence on the vertical vibration response of vehicle.In the frequency domain,based on pseudo-excitation method of railway vehicle response,the influence of different speed,suspension system parameters,air spring parameters on the power spectral density of vehicle system vibration response is obtained through MATLAB program.The results show that a phenomenon of vehicle and bogie response power spectral density curves move to the right is appearing with the increase of the speed.The influence of suspension system parameters on the power spectral density of vehicle system vibration response is different in different frequency bands.The influences of air spring parameters on the power spectral density of vehicle system vibration response are mainly concentrated in less than 10 Hz frequency range.Finally,Sperling index is adopted as an evaluation standard of vehicle stability.The influence rule of air spring parameters and suspension system parameters on vehicle running stability is researched.The speed,secondary damper,primary spring stiffness,effective areaare positively correlated with Sperling index.Additional volume,throttle diameter are negatively correlated with Sperling index.The results show it can effectively decrease the vibration of the vehicle by adopting the smaller effective area,the larger additional volume and the larger throttle diameter within an advisable range.