Modelling of air springs for metro vehicles and studies on the effect of orifice damping

With the metro vehicle as the subject, a mathematical model of the main chamber, the auxiliary chamber and the orifice of the air spring were established based on the thermodynamic theory. The lateral nonlinear model is obtained based on the analytical geometry. Establish the four-point levelling valve and differential valve models through theoretical analysis. A complete three-dimensional air spring model is established. The correctness of the model is verified by comparing it with the actual data. The impact of orifice diameters and secondary vertical dampers on the dynamic performance of the metro vehicle is investigated. The results show that the secondary vertical damping configuration has a greater effect on vertical stability and acceleration but a minor impact on operational stability. Metro vehicles equipped only with air springs in the smaller diameter orifice do not need to be configured with a vertical damper, resulting in excellent dynamic performance and savings in production costs.