空气弹簧动刚度模型关键非线性参数辨识及动态特性研究

Identification of Key Nonlinear Parameters and Research on Dynamic Characteristics of Air Spring Dynamic Stiffness Model

提出了一种考虑等效阻尼及滞回特性的乘用车用空气弹簧动刚度模型,给出模型中各部件物理意义及数学表达以适用于空气悬架的精确控制。基于模型解析表达式给出一套针对模型中有效面积等效刚度、空气气囊刚度和等效阻尼等关键非线性参数辨识的一般方法,设计示功试验对各参数项进行辨识并验证了在大行程下动刚度模型及参数辨识方法的正确性和可行性(大行程正弦激励下模型最大相对误差小于0.5%,参数辨识误差小于3%)。最后基于推导出的动刚度模型分析了关键参数的影响及其动态特性。结果显示,乘用车单腔室空气弹簧的滞回特性(相位角)随频率增大呈现先增大后减小的趋势。等效刚度越大相位角峰值越大且对应频率越高;等效阻尼越大相位角峰值不变,对应频率减小。根据理论和试验指明了空气弹簧关键非线性参数的频率相关性及其变化规律,为空气弹簧的理论建模及正向开发提供指导。

An air spring dynamic stiffness model for passenger cars considering equivalent damping and hysteresis characteristics is proposed. The physical meaning and mathematical expression of each component in the model are given for precise control of air suspension system. Based on the analytical expressions of the model, a set of general methods for the identification of key nonlinear parameters such as the effective area equivalent stiffness, air chamber stiffness and equivalent damping are given. The indicator experiment is designed to identify each parameter item, and verify the correctness and feasibility of the dynamic stiffness model and the parameter identification method under large stroke(the maximum relative error of the model under long-stroke sinusoidal excitation is less than 0.5%, and the parameter identification error is less than 3%). Finally, based on the derived dynamic stiffness model, the influence of key parameters and their dynamic characteristics are analyzed. The results show that the hysteresis characteristic(phase angle) of a single-chamber air spring for passenger cars increases first and then decreases with increasing frequency. The greater the equivalent stiffness, the greater the phase angle peak value and the higher the corresponding frequency;the greater the equivalent damping, the phase angle peak value remains unchanged, and the corresponding frequency decreases.According to the theory and experiment, the frequency dependence and change law of the key nonlinear parameters of the air spring are pointed out, which provides guidance for the theoretical modeling and forward development of the air spring.