Study On Handling Stability Of Air Suspension Bus

In recent years,with the rapid development of automobile industry,people's requirements on driving safety and riding comfort are gradually improved.The suspension system plays a decisive role in stability and comfort.The traditional bus mostly uses leaf spring suspension,which has some problems such as small bearing capacity,poor vibration absorption effect and great damage to the road surface.Therefore,air suspension with variable stiffness,good shock absorption and comfort stability has been widely used in cars and buses.The suspension system affects the dynamic performance of the vehicle.This paper studies the handling stability of air suspension bus.The main contents of this paper are as follows:Firstly,this paper analyzes the differences between air spring and traditional leaf spring in structure,stiffness characteristics and natural frequency.The main structure of air suspension is analyzed,including air spring,shock absorber and guide mechanism.The variable stiffness and natural frequency characteristics of air spring are analyzed.The performance of air spring is compared with that of leaf spring by theoretical formula derivation and combined with the performance test of air spring.The influence of air spring on vehicle handling stability,ride comfort and other performances is analyzed.Then the whole air suspension system is analyzed,through the analysis of front and rear air suspension structure and installation position,to understand the working principle of air suspension.According to the parameters of the bus,the dynamic model of the bus is established and the dynamic characteristics are simulated.It is a complex process to establish the dynamics of the whole vehicle.The degree of freedom of the model can be reduced by reasonable assumptions,and the single wheel model of the bus,i.e.the two degree of freedom 1/4 air suspension model,can be established.We should also consider the establishment of suspension related components,tire model and road model.Using Matlab/simulink simulation,the air suspension and leaf spring suspension in the body vertical acceleration,suspension dynamic travel and tire dynamic load three results are compared,combined with the evaluation index to analyze the impact of suspension on vehicle handling stability.At the same time,the problem of roll is ignored in the single wheel model,so the physical model and simplified mathematical model of the whole vehicle roll areestablished,and Matlab simulation is carried out to analyze the influence of roll angle on the whole vehicle.Finally,through the establishment of the air suspension bus model in the dynamic simulation software,the handling stability of the whole vehicle is studied.According to the national standard,four evaluation and simulation analysis are carried out,including steady-state return,steering return,steering wheel angle pulse input and hunting test.After the simulation analysis of the above test,the scores of the air suspension bus are obtained by evaluating the scores,and the handling stability of the air suspension bus is analyzed according to the scores.