气体泄漏超声检测系统的设计

电子机电论文编号:JD085    本份设计附开题报告,任务书,论文,原理图,PCB,程序,外文翻译,论文正文字数:12708,页数:36

目    录

引言  ………………………………………………………………………… 1
1  方案的选择与论证  ………………………………………………………1
1.1 方案一    ………………………………………………………………………………1
1.1.1 绝对压力法  …………………………………………………………………………1
1.2 方案二        …………………………………………………………………………2
1.2.1 压差法  ………………………………………………………………………………2
1.3 方案三    ………………………………………………………………………………2
1.3.1 超声波检测法…………………………………………………………………………2
2  气体泄漏检测的设计原理 …………………………………………………2
2.1 气体泄漏产生超声波……………………………………………………………………2
2.2 声压与泄漏量的关系……………………………………………………………………3
3  超声检测电路设计原理与各单元电路的概述 ……………………………4
3.1 电路系统的硬件实现过程………………………………………………………………4
3.2 各单元电路的介绍  ……………………………………………………………………5
3.2.1 超声探头的原理    …………………………………………………………………5              
3.2.2 前置放大电路  ………………………………………………………………………6
3.2.3 带通滤波器      ……………………………………………………………………7
3.2.4 精密检波电路    ……………………………………………………………………9
3.2.5 A/D转换电路   ………………………………………………………………………9
3.2.6 单片机与LCD、键盘的连接电路的设计 ……………………………………………10
3.2.7 本振电路 ……………………………………………………………………………14
3.2.8 混频电路 ……………………………………………………………………………15
3.2.9 低通滤波   …………………………………………………………………………15
3.2.10 音频功放电路………………………………………………………………………17
3.2.11 整流滤波电路与稳压电路…………………………………………………………17
4  超声检测的软件设计   …………………………………………………24
5  电路的调试过程  …………………………………………………………25
6  结论      …………………………………………………………………26
谢辞     ………………………………………………………………………27
参考文献   ……………………………………………………………………28
附录   …………………………………………………………………………29

摘  要

随着工业的发展，各种气体包括易燃易爆、有毒气体的种类和应用范围都得到增加，传统的气体泄漏检测方法，如压差法、气泡法等，有其局限性，不仅操作复杂，对技术人员要求较高，而且不具有实时性。迫切需要各种方法简单，准确性可靠的检测方法。本文介绍了一种气体泄漏超声检测系统,在分析小孔气体泄漏产生超声波的原理的基础上,阐述了该检测系统的原理及设计方案。该系统能对各种压力容器的孔隙泄漏所产生的微弱超声信号进行精确检测。该系统利用技术对泄漏所产生的超声波信号进行分析处理和声压级计算,从而实现对泄漏的检测及泄漏量的估算。通过超声波检测，正确地判断和定位产生泄漏位置，对于提高企业的生产效率，节约能源，确保安全具有重大意义。
    在通过对超声波性质的研究中，我们发现超声波是一种高频短波，并且它在空气中传播具有很强的方向性。基于此特性，我设计了一套超声波检测电路，该电路包括了模拟电路与数字电路，其中模拟电路包含了信号放大电路和音频处理电路；数字电路由单片机和LCD、键盘等外围设备组成。在对超声波信号的处理的过程中，信号经过放大滤波以后，一路交给单片机处理，并在显示屏上读出信号的强度与流速；另一路通过降频转化为可听声，从而实现检测的目的。

关键词：单片机 ；声压级； 本底噪声； 泄漏超声波

Abstract

Along with the industry development, each kind of gas including is flammable explosive, the virulent gas type and the application scope all obtains the increase, the traditional gas divulges the examination method, like presses the method of difference, Air bubble method and so on, has its limitation, not only operates complex, requests to the technical personnel high, moreover does not have timeliness. Urgent need each method is simple, accurate reliable examination method. This article introduced one kind of gas divulges the supersonic examination system, divulges in the analysis eyelet gas has in the ultrasonic wave principle foundation, elaborated this examination system principle and the design proposal. This system can divulge the weak supersonic signal to each kind of pressure vessel hole which produces to carry on the precise examination. This system to divulges the ultrasonic wave signal using the technology which produces to carry on analysis processing and the acoustic pressure level computation, thus realizes to the examination which divulges and divulges quantity　estimate. Through the ultrasonic wave examination, correctly the judgement and the localization produces divulges the position, regarding enhances the enterprise the production efficiency, saves the energy, guarantees safely has the great significance.
In through to the supersonic wave archery target research in, we discovered the ultrasonic wave is one kind of high frequency short wave, and it disseminates in the air has the very strong directivity. Based on this characteristic, I have designed a set of ultrasonic waves examinations electric circuit, this electric circuit has included the analogous circuit and the digital circuit, analogous circuit has contained the signal enlargement electric circuit and the audio frequency processing electric circuit; The digital circuit by auxiliary equipment and so on the monolithic integrated circuit and LCD, keyboard is composed. In to the ultrasonic wave signal processing process in, the signal after enlarges after the filter, a group gives monolithic integrated circuit processing, and on display monitor read signal intensity and speed of flow; Another group through falls the frequency to transform for may listen to the sound, thus realization examination goal.

Keywords：Monolithic integrated circuit; Acoustic pressure level; Background noise;
Divulges the ultrasonic wave