| Suspension is an important part of vehicle chassis system,which has significant impact on the driving performance of vehicle.Hydro pneumatic suspension is a kind of suspension system with hydraulic oil as the load medium and nitrogen as the elastic medium,and it is widely used in construction machinery and military vehicles because of its strong bearing capacity and nonlinear variation of stiffness and damping characteristics.Once the traditional passive oil and gas suspension system is designed,its stiffness damping characteristics can not be adjusted adaptively according to the road conditions,so it is difficult to guarantee the vibration isolation performance requirements of the vehicle under the large range of driving conditions.Therefore,the research of hydro pneumatic suspension with adjustable stiffness and damping has important academic significance and engineering application value.For the traditional adjustable mechanism of controllable suspension system,there exists a dilemma with sophisticated model construction,high accuracy and high energy consumption.To address this problem,this paper proposes a multistage adjustable hydro pneumatic suspension structure with control method based on high-speed on-off solenoid valve.The model construction,characteristic analysis,parameter determination and control design of the system are carried out in order to lay a theoretical and technical foundation for further improving the performance of the hydro pneumatic suspension system.Firstly,the structural design and model construction of the new multi-stage adjustable hydro pneumatic suspension system with stiffness and damping are completed.The structure and working principle of the new multi-stage adjustable hydro pneumatic suspension system with stiffness and damping are introduced in detail,and the various working modes of the system and the performance characteristics under different working modes are analyzed.Based on the theory of hydrodynamics and dynamics,the mathematical model of a new multi-stage adjustable hydro pneumatic suspension system with stiffness and damping is established.Secondly,based on the mathematical model simulation,the influence of different structural parameters on the stiffness and damping characteristics of the new multi-stage adjustable hydro pneumatic suspension system with stiffness and damping is studied.The main structural parameters affecting the system characteristics are mastered,and then the key component parameters of the new hydro pneumatic suspension system are determined according to the vehicle suspension design requirements.Thirdly,the engineering design of the key structure of the new hydro pneumatic suspension system is carried out,and the engineering test prototype of the new hydro pneumatic suspension system is formed.Based on the single channel servo excitation test bench,the mechanical characteristics test of the system test prototype is completed,and the model accuracy of the new hydro pneumatic suspension system is verified according to the test results.Finally,the vehicle suspension dynamics model is built,and the stiffness and damping characteristics of hydro pneumatic suspension system under different driving conditions are optimized by using particle swarm optimization algorithm.The mode switching control method is designed to obtain the optimal switching sequence of the stiffness damping working mode of the new hydro pneumatic suspension system under different driving conditions.The multi-mode switching controller of the system is established by using Simulink / Stateflow.The simulation results show that compared with the passive hydro pneumatic suspension,the new hydro pneumatic suspension system based on multi-mode switching control can greatly improve the performance indexes of suspension system,such as body vibration acceleration,suspension dynamic deflection and wheel dynamic load. |
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