转向柱后倾角对三轮汽车前轮自激摆振特性影响

为获得转向柱后倾角对三轮汽车摆振影响,以国产某型三轮汽车作为样车,对其转向系统进行了简化,建立了二自由度前轮摆振系统动力学模型。基于以上模型,运用数值计算方法,得到了随车速变化的前轮摆振系统振动特性及转向柱后倾角变化对其的影响。结果表明,减小转向柱后倾角,能有效减小三轮汽车前轮自激摆振的速度区间。而当车速较高,前轮摆振系统发生自激振动时,减小转向柱后倾角能有效地降低前轮自激摆振极限环幅值和频率,甚至消除自激摆振现象。     

某型越野SUV转向轮Hopf分岔导致摆振现象的研究

为研究四驱越野车辆的转向轮的摆振问题,本文以某型越野SUV为样车,采用非线性轮胎数学模型魔术公式,建立关于转向轮的单自由度摆振力学模型。根据力学模型建立运动方程,应用Hopf分岔定理进行定性分析,结果表明,以车速作为变量时,该摆振系统在某一速度分岔点处发生Hopf分岔;然后使用四阶龙格-库塔(Runge-Kutta)方法对摆振系统进行数值仿真计算,得出该系统的速度分岔图,数值计算与定性分析,得到的分岔点几乎一致。最后针对系统摆振幅值最大工况下的幅频特性进行了分析,并以主销后倾角为参数研究其对摆振的影响。本文研究结果为在设计阶段避开自激摆振和使用阶段抑制自激摆振提供理论参考。     

前轮定位参数与轮胎特性对前轮摆振影响的研究

前轮定位参数对前轮摆振的影响是极其复杂的,它不仅影响了前轮的几何特性,并且对摆振系统的运动,约束与受力状况均产生重要影响。本文建立了包括全部前轮定位参数的前轮摆振数学模型;并在轮胎试验的基础上,比较系统、全面地研究了前轮定位参数对前轮摆振的影响规律。本文还研究了轮胎蛇形运动频率对汽车动力学摆振的影响。     

某大客车转向轮摆振及影响因素的分析

考虑侧偏角和侧偏力之间的非线性关系,建立4自由度某大客车转向轮摆振模型。运用非线性动力学理论,确定转向轮发生自激摆振的Hopf分岔点：通过MATLAB＆Simulink软件建立大客车转向轮摆振仿真模型。通过仿真结果检验理论分析,并得到车速、转向系参数、横拉杆参数、质心位置、主销后倾角与转向轮自激摆振幅值或频率的关系曲线．找出影响自激摆振的敏感参数及敏感参数的适取范围,能有效减小或消除客车的自激摆振。     

干摩擦力矩对某独立悬架汽车前轮摆振影响研究

为了探究前轮摆振的影响因素,将运动副间隙处的干摩擦等效到前轮主销处．应用拉格朗日方程建立了3自由度摆振系统模型,并用Matlab对其进行了仿真计算。结果表明,汽车在较大的初始激励下才会激发摆振;较大的干摩擦力矩有利于抑制摆振。     

转向轮摆振引发的商用车整车振动特性研究

针对汽车转向轮摆振引发的转向盘和车身振动现象,选用某型轻卡商用车作为样车,考虑悬架及转向系统干摩擦和轮胎非线性,应用拉格朗日方程建立了包含转向盘和车身的整车十自由度振动力学模型,轮胎力选用魔术公式模型,干摩擦选用Stefanski-Wojewoda模型。运用数值分析方法,对由转向轮摆振引发的整车振动系统进行分析计算,结果表明前轮摆振诱发整车产生自激振动多极限环现象,大幅自激振动与初始激励大小相关;振动幅值随车速增加呈现先增后减趋势;干摩擦幅值增加,摆振幅值和区间都相应减小,且多环区间加大,中间过渡单环区间消失。     

汽车前桥摆振的稳定性分析

研究了减小和消除汽车转向轮摆振的方法,以五自由度前桥转向轮模型为研究对象,利用常微分方程稳定性理论和数值分析得出车速对前桥摆振的影响,而且发现改变某些参数可以完全消除摆振,改变某些参数对系统摆振没有明显影响,改变某些参数还可以引起二次摆振。     

轮胎侧向刚度对客车前轮摆振的影响分析

某型纯电动中型客车在良好路面高速行驶工况下出现方向盘小幅快速摆动,通过对前轮摆振形成机理进行分析,筛选出七个可能导致前轮摆振的因素,并用排除法对上述因素逐一分析确认,推测轮胎的特性参数存在差异可能是导致前轮发生摆振的原因。进一步通过对比测试故障车辆安装不同品牌轮胎时,方向盘Y向加速度的大小,确认导致车辆前轮出现摆振的原因为轮胎的特性参数存在问题。对比两款轮胎均匀性参数后发现,故障车辆匹配的轮胎因侧向力波动和侧向力偏移均较大、轮胎侧向刚度偏小,导致前轮摆振的幅值较大、前轮摆振系统稳定区域较小,是导致车辆出现前轮摆振的根本原因,最终通过更换其他品牌的轮胎有效解决车辆摆振问题。     

整体桥五连杆悬架前轮摆振的动力学分析

以轮胎与地面之间的受力分析为出发点,应用ADAMS 2013动力学软件,详细分析整体桥五连杆前悬架的性能参数变化特性,对引起前轮摆振的动力学原因进行详细阐述,指明在转向系统中加装阻尼器是解决悬架前轮摆振问题非常有效的方法。     

汽车操纵稳定性与前轮摆振的非线性仿真分析

以某轿车为例,建立3自由度整车系统动力学模型,利用常微分方程稳定性理论和数值仿真计算,详细研究整车的稳态转向特性和系统失稳后的前轮摆振特性。阐明汽车的操纵稳定性与前轮摆振特性同属汽车整车稳定性问题,前者是负刚度系统,后者是负阻尼系统。在一定的参数组合下,具有不同转向特性的汽车都或多或少地存在摆振现象,这与实际情况相符,建议适当增加转向系阻尼和刚度以减小甚至消除摆振的发生。     

Analysis of steering shimmy accompanied by sprung mass vibration on light duty truck — Fundamental mechanism

Steering shimmy phenomena are classified into two groups according to vehicle speeds. One is self-excited vibration at low vehicle speeds, and the other is forced vibration at high speeds. Shimmy on a light duty truck has been considered as that of self-excited vibration. However, it causes vibration not only on the steering system but also on the cabin, with a large amplitude at relatively high speeds. The phenomenon was analyzed by performing vehicle tests and numerical simulations using simplified models. As a result, the phenomenon was found to be self-excited vibration basically caused by two closed-loop vibration mechanisms.     

Energy analysis of the Von Schlippe tyre model with application to shimmy

Shimmy is an engineering example of self-excited vibrations. Much research on shimmy has considered the tyre as a positive feedback or negative damping to introduce instability of the entire system. In this context, we focus on the behaviour of the tyre under periodic excitations. The Von Schlippe tyre model is selected and the energy flow method is applied to illustrate the energy transfer by the tyre during shimmy. The energy flow method evaluates the tyre performance with a prescribed sinusoidal motion and provides a novel evaluation method for tyre models. With the help of straight contact line assumption in the Von Schlippe tyre model, the relative motion between the contact line and the wheel centre is studied to understand the path dependency of the energy transfer. It turns out that the tyre is extracting energy from the forward motion to induce unstable lateral and yaw vibrations when the motion or orientation of the contact line has a phase lead with respect to the wheel centre.     

关于车辆方向盘摆振的补偿方法及补偿系统研究

研究电动助力转向系统对方向盘摆振补偿的功能,通过对影响方向盘摆振因素的分解,当整车基本参数确定的情况下可以采用EPS进行摆振补偿.通过摆振补偿功能开发到某车型实车测试验证,有效解决高速制动等工况下方向盘摆振问题.该研究为车辆方向盘摆振问题的解决提供采用EPS补偿万式提供方法及系统.     

独立悬架汽车摆振的研究

以标致５０５ＳＬ轿车为研究对象，采用分析力学的方法，建立了前悬架为独立悬架的汽车转向轮摆振数学模型。通过对摆振系统特征的分析，确定了影响摆振的主要振动模态，得独立悬架汽车特有的摆振振型，并通过道路试验证实了研究结果的正确性。     

The Wheel Shimmy Problem: Its Relationship to Wheel and Road Irregularities

The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability.     

The Wheel Shimmy Problem: Its Relationship to Wheel and Road Irregularities

SUMMARY

The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability.