Abstract:The hydropneumatic suspension structure is simple and has high rigidity, which is widely used in engineering vehicles with complex excitation. According to the output force characteristics of the hydropneumatic suspension, the components of the output force were analyzed. The B-W-R real gas state equation was used to consider the dissolution characteristics of the gas in the oil and the damping force equation was obtained to establish a mathematical model of the output force of the hydropneumatic suspension. According to the mathematical model, based on Simulink, the simulation model was established. The gas pressure change and the damping force characteristics of the suspension under different saturated dissolution volumes were analyzed, considering the dissolution characteristics or not. The quarter vehicle suspension model was built, and the changes of the gas pressure and damping force under slow static loading and dynamic loading were analyzed, which were compared with the simulation results to verify the accuracy of the mathematical model. The results show that the gas pressure is greatly affected by the solubility;when the pressure rises, the mass of the remaining gas decreases due to the gas dissolution, which resulting in a decrease in pressure;while in the pressure decrease phase, the gas pressure rises due to the reduction of the pressure, and the gas pressure rises;considering the gas dissolution, the cutoff point of the gas pressure in the suspension is 0.95 MPa of the initial inflation pressure;when the gas is dissolved, the limit state pressure value is almost unchanged during the compression process of the cavity due to the gas dissolution characteristics, but in the extended state, the change is larger, and the extreme value is significantly smaller;the pressure value of the entire process is reduced from the initial 2 MPa to the final value of 1.5 MPa. The simulation results are basically consistent with the test results, indicating that based on the B-W-R real gas equation, considering the effects of gas dissolution and precipitation in oil, the mathematical model of the output force of the hydropneumatic suspension is highly reliable.It provides reference for such design.