Analyzing the Accuracy of the Air Suspension System Models Based on Two Different Calculation Methods

Based on the thermodynamic theory and the model of the air suspension system (ASS), two different calculation methods including Method I, using ASS’s initial parameters to calculate the mass flow rate and the total stiffness of the ASS, and Method II, using ASS’s initial parameters to determine the static stiffness, elastic stiffness, and damping coefficient of the ASS, are researched. To assess the accuracy of each calculation method and the ASS’s performance, a quarter-vehicle dynamic model equipped with the ASS and the steel spring is simulated and analyzed under the different excitations of the harmonic and random road surfaces. Experimental investigations are also used to verify the accuracy of the models. The research shows that the computation results of the two calculation methods I and II are similar under the same simulation conditions. In addition, the research results also indicate that Method I should be applied on the ASS’s model of two-axle vehicles equipped with an auxiliary air tank connected to multi-airbags via connecting pipes, and Method II should be used on the multi-axle vehicles in that each ASS of the vehicle consists of only one airbag connected with a separate reservoir. The investigation results not only reinforce the accuracy of the two calculation methods and the ASS’s performance but also carry out the advantages and disadvantages and the application scope of each calculation method.