Design And Study Of Car Seat Suspension

With the improvement of people's living standards,the application of automobiles has become more and more extensive,and at the same time,the driving comfort requirements for automobiles become higher and higher.The automotive seat suspension based on quasi zero stiffness has the characteristics of high static stiffness and low dynamic stiffness near the equilibrium position.Its initial vibration isolation frequency is very low,so it can effectively isolate low frequency vibration that is harmful to human body.And it has the advantages of simple structure,easy realization,reliable work and low cost.It has wide application prospect and is one of the developing directions of seat suspension.In this paper,a automobile seat suspension based on the positive stiffness mechanism and negative stiffness mechanisms in parallel is designed(The seat suspension structure has applied for a national invention patent: an adjustable high vibration isolation performance automobile seat suspension structure.No.: 201810245963.6).The static characteristics and vibration characteristics of the seat suspension were systematically studied through theoretical research,simulation analysis and experimental research.The main research contents and conclusions are as follows:(1)The stiffness characteristics of the seat suspension are theoretically studied.The influence of the pre-compression of horizontal spring on the stiffness of the seat suspension was analyzed,and the condition for the quasi-zero-stiffness characteristic of the seat suspension in equilibrium position were obtained.And the seat suspension requires an adjustment mechanism to adjust its static equilibrium position to a fixed specific position.The dynamic model of the seat suspension was established and solved.The displacement transmissibility characteristics of the seat suspension under different pre-compression of horizontal spring and the different equivalent damping were obtained,and the time domain response of the seat mount under different types of excitations were obtained.The research results show that when the excitation frequency is higher than 2Hz,the seat suspension has good vibration isolation performance,and the isolation rate is higher than 60%.(2)The structure of seat suspension was designed and divided into vertical spring installation and adjustment mechanism,negative stiffness mechanism,suspension height adjustment mechanism,guiding mechanism and so on to realize the adjustment function for occupants of different body weights and different heights.Structural design was performed for each mechanism and important parts were checked.Three-dimensional modeling of the designed parts were builded and they were virtual assembled in the UG software to check for interference and further optimization of the structure.(3)The ADAMS simulation model was established and simulated under different equivalent sprung mass and different frequency displacement excitation conditions.The simulation results show that the resonance frequency of the seat suspension is between 0.5Hz and 0.75 Hz,and the initial vibration isolation frequency of the suspension is about 1Hz.When the excitation frequency is higher than 2Hz,the isolation ratio of the seat suspension is more than 65%,and the greater equivalent sprung mass,the higher isolation rate.The simulation results are in accordance with the theoretical analysis results.(4)A prototype of seat suspension was built and its static characteristics were measured.The small stiffness region of the seat suspension prototype is about 40 mm,and the stiffness is about 3000N/m.A dynamic experiment system was built and experimentation was carried out.The experimental results show that the inherent frequency of the seat suspension prototype is about 1.4Hz,and the initial vibration isolation frequency is about 2Hz.When the excitation frequency is higher than 4Hz,the isolation rate is higher than 50%.The seat suspension has good vibration isolation performance.The research of this subject has confirmed that the seat suspension based on quasi-zero-stiffness has excellent vibration isolation performance and provides a new design solution for the suspension of the automobile seat.The research results have important reference value for the seat suspension design.