| Modern vehicles especially the construction vehicles, military tanks and other off-road vehicles will vibrate seriously when working. For off-road vehicles’drivers, who work and run in worse environment commonly, bear vibration of high strength and low frequency for a long time, their physical and mental health will be damaged seriously. Therefore, the research on seat suspension system and its dynamic performance to improve the comfort of off-road vehicles is much more worthwhile.In order to improve the ride environment of off-road vehicles, a new type semi-active seat suspension based on air spring with auxiliary chamber and MR damper was designed. In this study, the theoretical analysis model was set up, and the seat suspension prototype was designed and manufactured. Through bench test, the vibration characteristic was studied, and the simulation model for seat suspension ride was established. The completed work and achieved results are generalized as follows:(1) The overall program of semi-active seat suspension was designed. Based on the theory of rigid body dynamics, the theoretical model of suspension system was established, the calculation formula of the natural frequency, equivalent stiffness, equivalent damping and damping ratio were deduced, and the main factors of the semi-active suspension vibration characteristics were analyzed. The results show that, the performance of the seat suspension was influenced greatly by the equivalent sprung mass, excitation frequency, the air spring stiffness and MR damper damping.(2) Based on air spring with auxiliary chamber, solenoid proportional valve, MR damper and scissors linkage seat, a new type semi-active seat suspension prototype was designed and manufactured. The overall size and working stroke of the suspension system were determined. The air spring, auxiliary chamber, MR damper and other major components were designed. The key parts of the seat suspension were checked, and the semi-active seat suspension prototype fabrication and assembly was completed. (3) Based on the semi-active seat suspension prototype, experimental system for vibration characteristic was established, and the experimental results were studied. The vibration characteristic variations of the semi-active seat suspension changing with the equivalent sprung mass, excitation frequency, the adjustable voltage of the proportional valve and the input current of MR damper were studied. The results showed that, the displacement transmissibility and acceleration root would decrease with the increasing of equivalent sprung mass. The displacement transmissibility of system was the least when the adjustable voltage was2V, and acceleration root would decrease obviously with the increasing of the proportional valve. When the input current of MR damper increased, the displacement transmissibility of suspension system would decrease, but the acceleration root would increase, besides, when the excitation frequency is greater, a larger value of MR damper input current should be selected in order to improve system stability and security.(4) Based on the "vehicle body-seat-human body" vibration system, the vibration mathematical model of semi-active seat suspension was established, and the simulation model was established in MATLAB7.0/Simulink environment. Besides, the ride performance of the stiffness, damping adjustable semi-active seat suspension and conventional passive seat suspension was comparative analyzed in different conditions. The simulation results showed that, the response acceleration of semi-active seat suspension compared with the passive suspension, the average decay rate was16.8%, and the driver comfort of off-road vehicles improved effectively.The research of this project has important theoretical and practical value, because it not only can promote the research of driver’s seat suspension for off-road vehicles, but also can improve vehicle ride comfort and decrease the occurrence risk of occupational disease caused by vibration. |
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