| Hydro-pneumatic spring is used as spring and damping element of Hydro-pneumatic suspension. The spring force is provided by pressed gas while the force is transferred by oil. The hydro-pneumatic spring is equipped with hardening stiffness which can provide low stiffness in equilibrium position to fulfill ride comfort requirement without decreasing the buffer function. Equipped with damping unite along the oil line,the hydro-pneumatic spring can works as damper simultaneously. Increasing or decreasing the oil inside the spring can change the chassis clearance. It is obviously that using hydro-pneumatic suspension can improve the performance ride comfort and vehicle trafficability.Hydro-pneumatic suspension parameters design of a sport-utility vehicle is proposed to optimize the vehicle riding performance. The main research works are as following:First,a numerical model of hydro-pneumatic spring is established according to a hydro-pneumatic suspension of a sport-utility vehicle. The model is validated by hydro-pneumatic spring rig experiments. The nonlinear characters of stiffness and damping have been studied by numerical simulation,and the variables influence of ride comfort have been worked out.Second,roughness power spectral density of the time domain model of random road surface is established by harmony superposition method. The road model is validated by comparing to the standard road surface.Third,a half car model with a hydro-pneumatic suspension system is established with MATLAB to study the ride comfort performances. The hydro-pneumatic suspension parameters are optimized to improve the vehicle comfort significantly. |
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