Assessing the Efficiency of the Air Isolation System Based on the Mathematical Models

Two calculation methods of the lumped parameter model (LPM) and mass flow ratio (MFR) used to establish dynamics models of air isolation system (AIS) in vehicles are widely applied. However, the efficiency and application range of the LPM and MFR for the AIS of the vehicles have not been explained in detail. To clarify this issue, the numerical simulation and experiment of the AIS performed under the harmonic excitation are given to evaluate the accuracy of the LPM and MFR. The two-axle automobiles and multi-axle heavy trucks equipped with the AIS are also simulated to evaluate the efficiency of the AIS with the LPM and MFR in improving ride comfort and road friendliness. The study shows that with the single model of the AIS, measured and simulated result in AIS's force response, force-deformation characteristic, and dynamics stiffness-frequency characteristic with LPM and MFR are similar. Therefore, both methods could be applied to establish the dynamic model of the AIS. However, by applying the AIS on the two-axle and multi-axle vehicles, the MFR improves road-friendliness and comfort in two-axle automobiles better than the LPM, conversely, the LPM improves road-friendliness and comfort in multi-axle trucks better than that the MFR. Therefore, to more accurately assess the isolation efficiency of the AIS in improving road-friendliness and comfort in vehicle, the MFR should be applied to the AIS using the pipe designed by the parallel pipes or long pipes of two-axle vehicles whereas the LPM should be applied to the AIS using the pipe designed by the complex pipes of multi-axle vehicles.