液压系统油液有效体积模量的在线软测量

Online Measurement of Effective Bulk Modulus in Hydraulic System by the Soft-sensing Model

液压油的有效体积模量不仅是影响液压控制系统性能的重要参数,也是反映液压设备运行状态的特征参数。以液压油有效体积模量的在线监测为研究目的,利用瞬变流理论和气液两相流理论,在频域内建立液压系统管路中油液的固有频率、压力、气泡体积分数与有效体积模量关系的软测量模型,并对其进行数值仿真分析。该模型应用的关键问题是如何在线测量油液的固有频率,可行的解决方案是在液压动力系统选定的两个油液压力波动监测点安装压电式压力传感器,通过在线激励动态测量油液的压力频率响应函数,从而识别油液的固有频率。在液压动力系统多源诊断信息获取试验装置上对该模型进行试验验证。研究结果表明,该模型可以方便、有效地用于液压油的有效体积模量在线监测。

Effective bulk modulus of hydraulic oil is an important factor of dynamic characters in a hydraulic control system and it＇s regarded as one of the essential parameter for monitoring the condition of the sets at real operation.Based on transient flow theory and gas-liquid two-phase flow theory,a novel soft-sensing model is suggested for the online measurement of the effective bulk modulus and numerical simulations of the model are carried out.The model represents the relationship among natural frequency,pressure,bubble volume fraction and effective bulk modulus of oil in a straight pipe.The key problem of using this model in practice is how to measure the natural frequency online.The feasible solution is installing piezoelectricity type pressure sensors at two oil pressure fluctuation monitoring points selected in the hydraulic power system,and through online excitation,the oil pressure frequency response function is dynamically measured,thus the natural frequency of oil is identified.Moreover,the effective bulk modulus may be estimated by the above model.This model is tested on the experiment platform of multi-source information acquisition of the hydraulic system.The results indicate that the model can be used successfully in the online measurement of the effective bulk modulus of hydraulic oil.