发动机前端附件驱动系统关键零部件的建模与设计分析方法

Engine Front End Accessory Drive (FEAD) system is the mean of power transmission in conventional automobiles, and is a typical discrete-continuous system composed of mixed mechanical dynamics system. The emergence of hybrid technologies, specifically the belt-driven Integrated Started-generator(ISG), has placed higher demands on belt drives than ever before. The presence of an ISG in a FEAD system leading to premature belt failure. Therefore, two types of critical damping components including automatic tensioner and Overrunning Alternator Decoupler(OAD), are designed to be suitable for the FEAD system. Automatic tensioner consists of tensioner pulley, tensioner arm and torsional-spring-damping element.It maintains constant tractive tension of the belt spans adjacent to tensioner pulley. The dynamic performance of a tensioner is dependent on excitation amplitude and excitation frequency. OAD consists of a one-way clutch and a torsional-spring-damping element. Since the Moment of Inertia (MOI) of the rotor for an alternator is the largest among MOI of all pulleys in FEAD, and rotational speed of the rotor equal to two to three times the crankshaft speed, this leads to large rotational vibration of the alternator pulley and large slip ratio between belt and alternator pulley in cases of engine rapid acceleration and deceleration. OAD is an advanced vibration isolator to reduce torsional vibration of alternator rotor in a FEAD. Currently, there is little study about modeling and analytical method for the two types damping elements of FEAD system in hybrid vehicles. This project intends to research on modeling method of nonlinear dynamic characteristics of automatic tensioner, to study experiment method and modeling method of the OAD dynamic characteristics. Based on the FEAD system in a hybrid vehicle, the objective of this project is: (1) to establish the modeling method of dynamic characteristics of automatic tensioner;(2) to establish the experiment method of measuring the dyanmic characteristics of OAD; (3) to establish mathematical model for nonlinear rotational vibration analysis of a FEAD system equipped with two tensioner and an OAD.

张紧器和发电机单向离合解耦轮(Overrunning Alternator Decoupler, OAD)是汽车发动机前端附件驱动(Front End Accessory Drive,FEAD)系统中常用的两类减振元件:(1)张紧器能自动调节带中张力、维持带张力稳定；(2)OAD具有单向离合和减振作用，将大转动惯量电机转子的振动与FEAD系统各个轮和皮带的振动解耦。目前该两类减振元件在混合动力汽车FEAD系统中的建模分析方法的相关研究较少。项目拟研究张紧器非线性动力学建模方法；研究OAD动态特性试验、建模方法；提出FEAD系统中带有两个张紧器和一个OAD的混合动力学系统的建模方法和动态特性计算方法。项目以提出离散-连续系统组成、存在大量非线性因素的混合动力学系统的计算方法，解决附件驱动系统中存在较大惯量附件时的复杂混合动力学问题为最终目标.

1) 建立了张紧器有效系数表达式，并对其性能进行了分析；研究了张紧器布置对多楔带附件驱动系统动力性能的影响；以张紧器有效系数最大、带段最大横向振动幅值最小为目标对张紧器布置进行了优化设计和提出的张紧器布置的优化设计方法。.2) 建立了考虑带弯曲刚度的SBAD系统梁耦合振动模型,计算分析带拉伸刚度、弯曲刚度、带线密度对带段横向振动、带动张力和张紧臂摆角等振动性能的影响。并以带拉伸刚度、张紧器弹簧刚度和张紧臂长为设计变量对SBAD系统进行优化以改进SBAD系统的振动特性。.3) 测试了张紧器的动态特性，分析了预载扭矩、激振频率和激振振幅对张紧器动刚度和滞后角的影响。基于张紧器的预载扭矩、弹簧刚度、阻尼系数和张紧臂转动惯量四个参数，建立了表征张紧器扭矩-角位移关系的迟滞回线模型；.4) 为控制SBAD系统振动,以张紧器布置参数（包括张紧器安装位置和安装角）为设计变量,以张紧器有效系数最大、带段横向振动幅值最小为目标建立多目标和单一目标两种优化模型.通过对比两种优化方案，揭示了引入权重系数的单一目标优化法的有效性。.5) 测试了张紧器的静态力学特性，其评价参数包括张紧器的静刚度、初始扭矩和阻尼系数. 介绍了张紧器力--位移曲线的实验方法，以及张紧器扭矩--角位移曲线、性能评价参数的求解方法. .6) 建立轴向运动弦线在张力和带速的参数激励下的发动机前端附件驱动系统非线性动力学方程,并用摄动法计算引起带横向振动不稳定特性的主/次谐共振频率范围,为减小系统振动提供另一个优化方向。.7) 测试了单向离合解耦轮（OAD）的动态特性，并建立了其线性等效模型。测试对比了有无（OAD）对附件驱动系统动态特性的影响，结果表明，发动机急减速时OAD对减小系统振动作用明显。.8) 截至2016年12月为止，标注该项目51305085的成果中，发表论文共17篇，录用论文共17篇。其中EI共8篇；申请国家专利4篇，其中发明专利授权1篇，实用新型专利授权1篇；培养博士研究生2名。