Hydro-pneumatic Suspension On The Dynamic Performance Of Vehicle

Hydro-pneumatic suspension is a developed form of suspension in the mid 50s of last century, which combines the technique of suspension, hydraulic transmission and control, it not only has the basic properties of the conventional passive suspension, in slightly modified, it can approach or reach the performance of active suspension. It has a very outstanding performance, is suitable for large construction vehicles and off-road vehicle suspension form, and has broad prospects for industrial production and the huge market potential.Hydro-pneumatic suspension technology has been widely researched and applied to obtain a large number of practical results. Moreover, it applied to a variety of vehicle models including cars. At present, the research on the hydro-pneumatic suspension is not very depth, most of them research it remain in the level of theoretical and the introduction of technical, but the momentum is very quick. Professor Guo Konghui began to research on the hydro-pneumatic suspension very early, and proposed a variety of new patents for the hydro-pneumatic suspension, as the first person, he organizes a group to try to manufacture the new hydro-pneumatic suspension. This thesis is in view of a new type of hydro-pneumatic springs for Professor Guo's patent, and starting work combined with trial and properties research of the hydro-pneumatic suspension.This thesis introduced the history, working principle, classification and characteristics of the hydro-pneumatic suspension, and then analysed the hydro-pneumatic suspension status of the domestic and international in brief, and highlighted the core of this thesis-the hydro-pneumatic suspension system could lift and the oil and gas separation type of single chamber spring.Then this thesis analyzed the structure and working principle of the hydro-pneumatic spring, simplified the structure of it reasonably, abstract spring out of the oil and gas equivalent physical model and physical model based on a nonlinear mathematical model. I participated in the trial of the hydro-pneumatic spring, and Completed the performance test and endurance test. Moreover, We researched on the design theory of the hydro-pneumatic suspension, and established the auxiliary design software.I established the hydro-pneumatic spring model by AMESim, simulated on its outside characteristics, and compared the simulation results with the experimental results, then researched on the influence of the damping and stiffness characteristics on hydro-pneumatic spring by the structural parameters.Finally, I established the vehicle model of hydro-pneumatic suspension by CarSim, simulated on the vehicle simulation model, researched on the influence of the vehicle handling and stability by the hydro-pneumatic suspension, and then evaluated the simulation results.The main findings of this thesis including:it has accumulated the valuable experience of trial performance and durability testing data for the hydro-pneumatic suspension, prepared the way of developing and producing the new hydro-pneumatic suspension; established the simplified physical model and non-linear mathematical model for the single-chamber pneumatic spring, provided the theoretical basis for the simulation; AMESim external characteristics of the model simulation results are consistent with the outside characteristic or trend of the test, indicating that the establishment of the AMESim model for hydro-pneumatic spring is right, and it can be used to guide the trial of manufacture hydro-pneumatic spring; analysed the influence for the external characteristics of hydro-pneumatic spring by the structural parameters, so it can be used to direct the design and optimize for the structural parameter of hydro-pneumatic spring. Set up 1/4 vehicle model and full vehicle dynamics model for the hydro-pneumatic suspension, advanced the dynamic performance simulation for the test car of hydro-pneumatic suspension, the simulation results show that in varying degrees, the hydro-pneumatic suspension can improve the vehicle handling, stability and ride. This thesis achieved the desired objectives, and it laid a solid foundation for the vehicle test in future.