Research On Vibrtion Characteristic Of One New Seat Semi-Active Suspension System

In order to further reduce the vibration transmitted from vehicle to driver, seat suspensions have been very important. Based on seat semi-active suspension system, the stiffness and damping could be adjusted adaptively without external energy input. Besides, seat semi-active suspensions have not only the good vibration isolation performance of active suspensions but also the simple structure and low-cost advantages of passive suspensions. As a result, seat semi-active suspensions would have a wide range of applications, and be one direction of the seat suspension developments.A new model of the seat semi-active suspension was put forward, the vibration characteristics of which was systematically researched by theoretical analysis, experimental research and simulation methods. An air spring with auxiliary chamber, a proportional flow valve and a MR damper were between the face and floor of the seat. The variations of the seat displacement transmissibility and response acceleration changing with the input voltage of the proportional valve and the input current of MR damper were found in different conditions of air spring pressure, sprung mass and excitation frequency. Besides, the optimal parameters in different sprung mass were obtained by experiments. The completed work and achieved results are generalized as follows:1. A new seat semi-active suspension with air spring and MR damper were designed. Based on the non-linear dynamics theoretical model of the air spring with auxiliary chamber and D'Alembert principle, the theoretical model of the seat suspension and its motion differential equation were established, the calculation formula of the equivalent stiffness, equivalent damping, natural frequency and damping ratio deduced, and the influence on the equivalent stiffness, equivalent damping, natural frequency and damping ratio was analyzed in different air spring location, air spring pressure, sprung mass, excitation frequency, input voltage of proportional valve and input current of MR damper.2. Experimental system for vibration characteristic of the seat semi-active suspension was established, and the experimental results were studied. Developed the new seat semi-active suspension prototype, established the test system for vibration characteristic, in which the equivalent stiffness and damping could be adjusted by changing the input voltage of the proportional valve and the input current of MR damper. Besides, the vibration characteristic variations of the seat semi-active suspension changing with the input voltage of the proportional valve and the input current of MR damper were found in different conditions of air spring pressure, sprung mass and excitation frequency, and the optimal parameters in different sprung mass were obtained.3. The simulation model of seat semi-active suspension was established in ADAMS, and the vibration characteristics was analyzed in different excitation frequency and input current of MR damper. The research results of theoretical analysis, experiment and simulation were compared and analyzed, and the control strategy of the seat semi-active suspension system was put forward.4. The results of theoretical analysis, experiment and simulation showed that, the resonance frequency of the seat suspension system could be adjusted by controlling the input voltage of the proportional valve, and it would decrease with the increasing of the voltage. When the voltage changed from 2.2V to 2.8V, the resonance frequency mutated from 2Hz to 1.5Hz. The input current of MR damper had a strong influence on the displacement transmissibility and response acceleration root mean square value only when the voltage of the proportional valve was zero, at this time, the increasing of the current could reduce the displacement transmissibility and response acceleration root mean square value in resonance frequency obviously. But in other voltage values, the input current of MR damper had little effect on them, because the damping caused by the air spring with auxiliary chamber increased with the proportional valve voltage and became the main effect factor.A new design proposal of seat semi-active suspension system for off-road vehicles is provided by the research of this project, and the research results have reference value for the design of the system.