【作者】 黄伟；

【导师】 邓兆祥；

【作者基本信息】 重庆大学 ， 车辆工程， 2018， 硕士

【摘要】 随着人们生活水平的提高,汽车的使用越来越广泛,同时对汽车的驾乘舒适性要求也越来越高。基于准零刚度的汽车座椅悬置在其平衡位置附近具有高静刚度低动刚度特性,其起始隔振频率很低,能有效隔离对人体伤害较大的低频振动,同时具有结构简单、易于实现、工作可靠和成本低等优点,有广泛的应用前景,是座椅悬置的发展方向之一。本文设计制造了一种基于正刚度机构(竖直弹簧)与负刚度机构(水平预压缩弹簧)并联的汽车座椅悬置(该座椅悬置结构已申请国家发明专利:一种可调的高隔振性能汽车座椅悬置结构,申请号:201810245963.6),通过理论研究、仿真分析和试验研究等手段系统的研究了该座椅悬置的静力学特性和振动特性。其主要研究内容和结论如下:(1)理论研究了座椅悬置的刚度特性,分析了水平弹簧预压缩量对刚度的影响规律,得到座椅悬置在平衡位置具有准零刚度特性的条件,且该座椅悬置需要调节机构调整其静平衡位置到一个固定的特定位置。对座椅悬置建立动力学模型并对其求解,分别得到座椅悬置在不同水平弹簧预压缩量和不同等效阻尼下的位移传递率特性,和座椅悬置在不同类型激励下的时域响应。研究结果表明,当激励频率高于2Hz时,座椅悬置具有良好的隔振性能,隔振率高于60%。(2)对座椅悬置进行结构设计,将其分为竖直弹簧安装与调节机构、负刚度机构、悬置高度调节机构、导向机构等机构,实现其对不同体重、不同身高乘员的调节功能。对每个机构进行结构设计,并对重要零件进行校核。对设计的零件进行三维建模并在UG软件中进行虚拟装配,检查是否有干涉和进一步优化结构。(3)建立ADAMS仿真模型,在不同等效簧载质量、不同频率位移激励条件下进行仿真。仿真结果表明:座椅悬置的共振频率出现在0.5Hz~0.75Hz之间,悬置的起始隔振频率约为1Hz;当激励频率高于2Hz时,座椅悬置的隔振率在65%以上,且等效簧载质量越大,隔振率越高。仿真结果与理论分析结果相符合。(4)制造了座椅悬置样机,测量了其静力学特性,座椅悬置样机存在小刚度区间,范围约为40mm,刚度约为3000N/m。搭建了动力学实验系统,并进行实验。实验结果表明,该座椅悬置样机的固有频率约为1.4Hz,起始隔振频率约为2Hz,当激励频率高于4Hz时,隔振率高于50%。该座椅悬置具有良好的隔振性能。本课题的研究证实了基于准零刚度的座椅悬置具有优异的隔振性能,为汽车座椅悬置提供了一种新的设计方案,研究结果对座椅悬置设计有重要参考价值。更多还原

【Abstract】 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.更多还原