Characteristics Analysis And Parameter Optimization Of Hydro-pneumatic Spring Damper

Compared with other forms of suspension,hydro-pneumatic suspension has the advantages of compact structure,unit energy storage ratio and excellent damping performance,so that it has been widely used for engineering vehicles and heavy off-road vehicles.The hydro-pneumatic spring works as the key component of hydro-pneumatic suspension and the damping valve is the main component to output damping force.Compared with the traditional damping valve which integrated in the piston,the independent type damping valve has the advantages of easy installation,convenient replacement and good heat dissipation,the independent type damping valve has a good application prospect in hydro-pneumatic spring or hydraulic damper.A certain type of damping valve of SUV with hydro-pneumatic spring has been researched.The simulation model was built by Solidworks and ANSYS Workbench software and the accuracy of model was verified based on bench test.The characteristics of the independent type damping valve were presented in this paper by using fluid-solid coupling method.The influence of oil temperature and structural parameters on the characteristics of the independent type damping valve were also explored,and the structural parameters of the independent type damper were optimized to improve the comprehensive performance of the hydro-pneumatic spring.Combined with the structure and working principle of hydro-pneumatic spring and independent type damping valve,the large deflection deformation analytic expression of the damping valve plate was deduced based on the theories of material mechanics and fluid mechanics.The mathematical model of the output damping force of the independent type damping valve was built based on the calculation of the orifice flow and the deformation principle of the damping valve plate.The 3D models of independent type damping valve and flow field were built through Solidworks software,and the fluid-solid coupling model and its solver were completed in ANSYS Workbench.After that,the detailed information of oil flow and the dynamic response of damping valve plate under the action of oil were obtained.The test plan of hydro-pneumatic spring was set up,then the 1/4 vehicle test bench was built according to the test plan.After that the bench test for hydro-pneumatic spring equipped with independent type damping valve was implemented,so that the accuracy of fluid solid coupling simulation model was verified.In addition,the influence of structural parameters and oil temperature on the characteristics of damping was explored.The damping coefficient in four stages(included before and after the valve open during compression trip and extension trip)was calculated,then,the damping coefficients from theoretical calculation in four stages were optimized according to genetic algorithm.The curve fitting method based on the velocity characteristic curve was used to optimize the structural parameters,including the diameter of constant throttling orifice,the thickness of the compression plate and extension plate.The result showed that compared with the result under initial parameters,the error between the aim value and actual damping value could be reduced by 9.79% and 7.79% in compression trip and extension trip respectively under optimized parameters.