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超声波检测液体流量已经逐渐应用于生活中,但是存在测量精度不高的问题.本文就影响系统测量精度的因素展开了研究.首先介绍了时差法超声波流量检测液压系统的工作原理,分析了影响系统测量精度的因素,得出超声波在流体中的声速变化对系统测量精度有重大影响的结论.针对液压系统工作过程中负载变化引起管路内压力变化,从而引起超声波的声速变化,进一步影响系统的测量精度的问题,在实验室中建立了压力一声速模型检测两种常用液压油的工作特性,采用多次测量取平均值的方法记录实验结果,根据实验数据利用线性回归分析理论推导出两种常用液压油的压力一声速关系.利用此关系式可以方便地计算不同压力情况下的声速值,为降低了压力变化对超声波流量检测系统的影响,提高系统测量精度提供了一种参考.,Ultrasonic flow detection systems have many applications but the measurements suffer from low precision.The purposes of this paper are to analyze the factors that influence such a system,and to develop a method for improving the system’s precision.The authors introduced the principle of ultrasonic flow detection based on the time-difierence method applied in a hydraulic pressure system,and analyzed the factors that influence the system.We found that the precision of the measurements is influenced by the pressure vailations,and established a model of pressure/velocity for ultrasonic measurements of hydraulic oil.1]he performance of two types of common hydraulic oil was measured in the laboratory,and the experimental results were obmined by averaging multiple datum points.The relationship between the pressure and the velocity of the ultrasonic waves for the two types of oil was determined by linear regression of the experimental data.The velocity of the ultrasonic waves under the changing pressures could be acquired with the relationship,providing a reference for reducing the influence of pressure variation and increasing the precision ofultrasonic flow detection systems.