考虑驱动电机激振的电动车油气悬架系统振动分析

电传动车辆中轮边驱动电机壳体振动直接作用于悬架下端,为评价电机激振力对悬架系统的输出影响,在考虑电机—路面不平度耦合激励影响下构建系统运动微分方程组进行分析。应用气体状态方程和油液孔口出流方程建立了单气室油气悬架非线性数学模型,采用麦克斯韦应力法对异步电机竖直方向激振力进行求解,采用白噪声滤波法模拟时域内随机路面,将耦合激励信号作用于系统模型,将悬架输出力和电机激振力带入系统运动方程组联立求得数值解,改变参数可进行多工况下平顺性仿真,并通过实车试验与耦合振动模型进行了对比。结果表明在常见正弦路面激励下,在考虑电机激振影响下系统输出振幅约增大10%且达到稳定所需时间更长。高频激振力使系统加速度功率谱幅值变大,在激振力自身频率段影响明显,不可忽略。通过分析实测数据与仿真数据,验证了耦合激励模型在实车中的有效性;耦合激励模型对电动车悬架及整车平顺设计有指导意义。

Vibration analysis of hydro-pneumatic suspension system based on drive motor excitation force

Abstract: Hydro-pneumatic suspension has good nonlinear elastic and damping characteristics and is widely used in engineering vehicles. Accurately establishing a mathematical model of hydro-pneumatic suspension systems and a vehicle dynamics model is important to analyze the dynamic characteristics and vehicle ride comfort. Scholars usually study the vibration of a suspension system only based on the excitation of road roughness. However, engineering vehicle suspension is directly connected to the wheel drive motor shell, and the vibration forces can directly act on the suspension. It is necessary to consider coupling excitation of the drive motor and road roughness to analyze the practical vibration characteristics of the engineering vehicle suspension system. This paper took the pneumatic suspension vibration system in a mine dump truck as its study object. The method of describing the movement of the real vehicle pneumatic suspension systems approach was proposed based on the combined effect of motor excitation and road roughness. According to the vehicle system installation, the author drew out a system model, conducted various stress analysis, and created the system equations of motion. The gas elastic force term could be seen as an ideal gas processing and pressure was equal to the suffered loads when the suspension was in a static equilibrium position. The damping force term was calculated using a thin-walled holes mathematical model. The relative displacement was taken as an argument to establish the damping force equation. According to the geometry and electromagnetic parameters of the driving motor, its finite element analysis model was established by software to obtain the flux density distributions. The vertical excitation force of asynchronous motors was solved by a Maxwell-stress method. The numerical solution of the electromagnetic force at the given speed was calculated and imported into the system equations. Road roughness was the major incentive to the driving of the vehicle and it could be described by a stationary stochastic process theory. In this paper, a white noise filtering method was adopted to simulate random road. This paper made a simulation comparison on the ideal sine road. The vehicle tests on an ISO D level typical road and obstacle negotiation proceeded to verify the validity of the theory. The results showed that on a typical sinusoidal road surface, the difference was most obvious in the initial time after considering the motor excitation. The system output amplitude increased by about 10% and took a longer time to stabilize. The suspension output elastic force changed significantly, and the two frequencies tended to finally coincide. The vehicle tests showed that the high-frequency excitation force made the system acceleration power spectrum become larger under various conditions, and the coupled excited vibration model was more consistent with the measured data. Power spectrum analysis showed that acceleration increased significantly in the exciting force frequency and should not be ignored. In the evaluation of suspension ride comfort, human acceptable vertical amplitude decreases with increasing frequency. High-frequency vibration effects will be more obvious and should not be ignored. The comparison of measured data and simulation verified the effectiveness of the motor incentive model in the pneumatic suspension system. To ensure the ride comfort of the whole vehicle with an in-wheel motor, motor excitation force and road excitation should be considered simultaneously in the suspension design.