| Vehicle suspension system is the assembly that attaching the frame to thewheel and axle. The function of the suspension system is to absorb the roadunevenness and to prevent them from being transmitted to the othercomponents of the vehicle．As an indispensable part of a vehicle, suspensionsystem plays a great role in keeping the quality of ride and safe performance.As a special form of suspension， the Hydro-pneumatic suspensioncombined with hydraulic transmission technology and vehicle suspensiontechnology. It possess the basic attributes of the traditional passivesuspension, what is more, it can approach the excellent performance of theactive suspension with appropriate design. The Hydro-pneumatic suspensionsystem can guarantee vehicles minimum ground clearance and its naturalvibration’s frequency does not change due to the reduce of the load, what ismore, it can reduce the vibration of pitch and roll of the vehicle. Moreimportantly, the damping and spring characteristics of Hydro-pneumaticsuspension system is rigorous nonlinear, these make great contribution toimproving the ride performance of ride. Hydro-pneumatic suspension system iswildly used in heavy-duty vehicles, engineering vehicles and military off-roadvehicles nowadays.This paper studies the Hydro-pneumatic suspension system basing on amilitary off-road vehicle. The main research work is detailed as below:Firstly, an over view of the type and technical characteristics of ahydro-pneumatic suspension are introduced. And the current researchsituation of Hydro-pneumatic suspension system in and abroad is brieflyanalyzed. Then the physical structure and working principle of a single airchamber Hydro-pneumatic suspension is detailed. Then a mathematical model of the hydrocarbon suspension is established based on its physical model.Simulation and test are adapted to validate the model.Secondly, the influence of the external characteristics of the hydrocarbonsuspension due to the variation of structure parameters is studied. Themathematical model of the stiffness characteristics and damping characteristicis established, to analyze the effect to vehicle ride and safe performancecaused by nonlinear characteristics of stiffness and damping. Finally, thefactors affecting the stiffness characteristics and damping characteristics arefocused，this lay the scientific and theoretical foundation for the designcalibrate and optimize the suspension system.Thirdly, a half car module applied with Hydro-pneumatic suspensionsystem is adapted to study the improvement to ride performances. To comparethe superiority between the Hydro-pneumatic suspension system and passivesuspension system, typical simulations in different driving condition areconducted. The great advantage of the Hydro-pneumatic suspension systemcan be told by the results.Finally, in order to take the greatest advantage of the Hydro-pneumaticsuspension system, we optimize the suspension system parameters to obtainthe best ride performance. This properties improve vehicle comfort significantlywithout breaking the vehicle safety requirements，achieve a good matchingbetween pneumatic suspension system and vehicle system. |
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