车用增程器扭振特性优化与鲁棒性分析

Optimization and Robustness Analysis of the Torsional Vibration Characteristics of a Vehicular Range-Extender

针对某款带有双质量飞轮(dual-mass flywheel,DMF)的混合动力汽车增程器轴系,进行了扭振特性多目标多参数优化与鲁棒性分析。首先在系统仿真软件Amesim中搭建了其扭转动力学模型,通过对比仿真与实测的增程器轴系自由端转速波动验证了模型,发现模型能较好地与试验结果吻合。选取轴系各段转动惯量、扭转刚度及阻尼等14个主要设计参数作为待优化参数,并以轴系强度、刚度与低阶固有特性等要求为约束条件,采用第二代非支配排序遗传算法(non-dominated sorting genetic algorithmⅡ,NSGA—Ⅱ)对轴系总惯量、典型稳态工况下关键节点角加速度与节点间传递扭矩之和等6个扭振特性指标进行了多目标优化。最后分析了单参数扰动情况下的轴系扭振系统鲁棒性。结果表明:双质量飞轮弹簧疲劳强度及轴系低阶固有特性等达到了约束条件要求,且大部分评价指标有所改善;减振皮带轮与主飞轮角加速度指标鲁棒性较好;在给定扰动条件下,2 阶模态阻尼比有一定概率不满足设计约束,部分设计参数的扰动超出许用范围。

Multi-objective multi-parameter optimization and robustness analysis of the torsional vibration characteristics was carried out for the range-extender’s shaft system equipped with a dual-mass flywheel(DMF)in a hybrid electric vehicle.The torsional dynamic model was developed in the simulation software Amesim.The model was then verified by comparing the simulated and measured speed fluctuations at the free end of a range-extender shaft system,and it was found that the model can reproduce the experiment results well.Fourteen main design parameters such as inertia,torsional stiffness and damping of each shaft segment were optimized for six torsional-vibration objectives including the total inertia of the shaft system,key nodes’angular acceleration and the sum of torque transmitted between nodes at the range-extender’s typical steady-state working conditions.The non-dominated sorting genetic algorithmⅡ(NSGA—Ⅱ)method was used and the constraints of the shafting strength,deformation and low-order natural torsional vibration characteristics were adopted.The design robustness of the shaft system was analyzed with the use of separated parameterperturbations.Results show that the fatigue strength of DMF springs and low-order natural torsional vibration characteristics are improved to meet the constraints and most of the optimization objectives are achieved.And the damping pulley and the primary flywheel angular acceleration are of good robustness.However,under the given disturbance conditions,there is a certain probability that the second-order modal damping ratio does not meet the design constraints,and the disturbances of some design parameters exceed the allowable ranges.