Critical threshold of the differential pressure valve in the air spring system of straddle monorail vehicles

Abstract

This study examines the critical role of the differential pressure valve in enhancing the anti-overturning performance of the air spring system in straddle monorail vehicles, focusing on determining its activation thresholds under various operational conditions. In straddle monorail systems, the narrow track beam width requires stabilizing and guiding wheels to bear complex tilting torques, making stability crucial during curve negotiation and asymmetric loading. A dynamic model of the straddle monorail vehicle is established, and the air spring system is characterized using a modular modeling approach, encompassing the main air chamber, auxiliary chamber, connecting pipes, height control valve, and differential pressure valve. Through theoretical analysis and MATLAB/UM co-simulation, the study validates the significant influence of the differential pressure valve on the vehicle’s anti-overturning capacity. The study further defines the upper and lower activation thresholds of the differential pressure valve: the lower threshold ensures the valve remains closed when stabilizing wheel pre-pressure is above zero, maximizing the air spring system’s anti-overturning torque, while the upper threshold prevents guide wheel detachment under high lateral torque, ensuring safe curve negotiation. Simulation results indicate an optimal activation range for the differential pressure valve between 95 and 110 kPa effectively maintains lateral stability under high tilting moments and air leakage conditions. The findings provide a robust technical basis for configuring the differential pressure valve in air spring systems for straddle monorail vehicles, contributing to enhanced safety and reliability under complex operational scenarios.