用于超小管径脉动流量的超声流量计新方法  

A Novel Method of Ultrasonic Flowmeter For Ultra-small-diameter Pulsating Flow

作　　者：程海凭[1] 王选[1] 赵广宇 

机构地区：[1]上海医疗器械高等专科学校医学电子与信息工程系,上海200093 [2]威海威高血液净化制品有限公司上海分公司,上海200021

出　　处：《中国医学物理学杂志》2013年第3期4184-4188,4204,共6页Chinese Journal of Medical Physics

基　　金：军队"十二.五"重大项目(AWS11J03)

摘　　要：目的:为了解决超声流量计在超小管径脉动流量测量中的测量精度不高的问题,研究一种新的解决方法及其技术方案。方法:分析了时差法超声流量计的原理,得出其技术关键在于时间的精确测量,对现有的几种时间测量方法进行了分析。针对超小管径脉动流量的特点,借鉴并改进了其中有参考价值的环鸣法和时间变换法。结果:提出了一种交替环鸣时间变换的新方法。给出了实现这种方法的系统硬件设计框图。同时对于系统中提高测量精度的关键技术进行了分析,诸如测量时间点的精确捕捉、时间-电压转换系数对称性措施、无关时间的抵消和电路非对称延时的调零消除等,给出了具体的方案措施。结论:该方法既克服了一般环鸣法的缺点,又结合了时间变换法的优点,可以提高超声流量计在超小管径脉动流量中的测量精度,提供了一种结构简单、易于实现的新的解决方案,拓展了超声流量计的应用范围。运用此方法成功地解决了在血液净化机中测量超小管径超低脉动的血流量的问题。Objective： In order to solve the problems of measurement precision in the application of ultrasonic flowmeter in ul- tra-small-diameter pulsating flow, a novel method and its technical implementation scheme was studied. Methods： The princi- ple of time difference for ultrasonic flowmeter was analyzed, The key technology was to measure the time accurately. There- fore, several existing methods for measuring time were analyzed. For the characteristics of ultra-small-diameter pulsating flow, the time conversion method and the sing-around method were adopted and improved. Results： A novel method of alternative sing-around and time conversion was proposed. The hardware design diagram for the method was also supplied. The key tech- niques of the method, were also analyzed and corresponding solutions were also supplied, such as accurate capture of measur- ing time, a symmetry method for time-voltage conversion coefficient, offset of unrelated time delay and zero elimination of cir- cuit asymmetric delay. Conclusions： The novel method not only overcame the drawback of general sing-around method, but also has the advantages of time conversion method. The method will improve the measurement accuracy of ultrasonic flowme- ter for ultra-small-diameter and pulsating flow. It provided a novel solution of simple structure and easy implementation. It ex- tended the application scope of ultrasonic flowmeter. This method solved the problems successfully in the application of ultra- sonic flowmeter in ultra-small-diameter pulsating flow in blood purification device.

关 键 词：超声流量计 超小管径脉动流量 时差法 时间测量 交替环鸣时间变换法 

分 类 号：TH814[机械工程—仪器科学与技术]