Li Xue, Song Zhengxiang
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Sensors (Basel). 2015 Apr 9;15(4):8253-65. doi: 10.3390/s150408253.
Liquid pressure is a key parameter for detecting and judging faults in hydraulic mechanisms, but traditional measurement methods have many deficiencies. An effective non-intrusive method using an ultrasound-based technique to measure liquid pressure in small diameter (less than 15 mm) pipelines is presented in this paper. The proposed method is based on the principle that the transmission speed of an ultrasonic wave in a Kneser liquid correlates with liquid pressure. Liquid pressure was calculated using the variation of ultrasonic propagation time in a liquid under different pressures: 0 Pa and X Pa. In this research the time difference was obtained by an electrical processing approach and was accurately measured to the nanosecond level through a high-resolution time measurement module. Because installation differences and liquid temperatures could influence the measurement accuracy, a special type of circuit called automatic gain control (AGC) circuit and a new back propagation network (BPN) model accounting for liquid temperature were employed to improve the measurement results. The corresponding pressure values were finally obtained by utilizing the relationship between time difference, transient temperature and liquid pressure. An experimental pressure measurement platform was built and the experimental results confirm that the proposed method has good measurement accuracy.
液体压力是检测和判断液压机构故障的关键参数，但传统测量方法存在诸多不足。本文提出了一种有效的非侵入式方法，利用基于超声波的技术测量小直径（小于15毫米）管道中的液体压力。该方法基于超声波在克内泽液体中的传播速度与液体压力相关的原理。通过在不同压力（0帕和X帕）下液体中超声波传播时间的变化来计算液体压力。在本研究中，时间差通过电处理方法获得，并通过高分辨率时间测量模块精确测量到纳秒级。由于安装差异和液体温度会影响测量精度，采用了一种特殊类型的电路，即自动增益控制（AGC）电路和考虑液体温度的新型反向传播网络（BPN）模型来改善测量结果。最终利用时间差、瞬态温度和液体压力之间的关系获得相应的压力值。搭建了实验压力测量平台，实验结果证实了该方法具有良好的测量精度。
