氣體泄漏超聲檢測系統的設計

電子機電論文編號:JD085    本份設計附開題報告,任務書,論文,原理圖,PCB,程序,外文翻譯,論文正文字數:12708,頁數:36

目    錄

引言  ………………………………………………………………………… 1
1  方案的選擇與論證  ………………………………………………………1
1.1 方案一    ………………………………………………………………………………1
1.1.1 絕對壓力法  …………………………………………………………………………1
1.2 方案二        …………………………………………………………………………2
1.2.1 壓差法  ………………………………………………………………………………2
1.3 方案三    ………………………………………………………………………………2
1.3.1 超聲波檢測法…………………………………………………………………………2
2  氣體泄漏檢測的設計原理 …………………………………………………2
2.1 氣體泄漏產生超聲波……………………………………………………………………2
2.2 聲壓與泄漏量的關系……………………………………………………………………3
3  超聲檢測電路設計原理與各單元電路的概述 ……………………………4
3.1 電路系統的硬件實現過程………………………………………………………………4
3.2 各單元電路的介紹  ……………………………………………………………………5
3.2.1 超聲探頭的原理    …………………………………………………………………5              
3.2.2 前置放大電路  ………………………………………………………………………6
3.2.3 帶通濾波器      ……………………………………………………………………7
3.2.4 精密檢波電路    ……………………………………………………………………9
3.2.5 A/D轉換電路   ………………………………………………………………………9
3.2.6 單片機與LCD、鍵盤的連接電路的設計 ……………………………………………10
3.2.7 本振電路 ……………………………………………………………………………14
3.2.8 混頻電路 ……………………………………………………………………………15
3.2.9 低通濾波   …………………………………………………………………………15
3.2.10 音頻功放電路………………………………………………………………………17
3.2.11 整流濾波電路與穩壓電路…………………………………………………………17
4  超聲檢測的軟件設計   …………………………………………………24
5  電路的調試過程  …………………………………………………………25
6  結論      …………………………………………………………………26
謝辭     ………………………………………………………………………27
參考文獻   ……………………………………………………………………28
附錄   …………………………………………………………………………29

摘  要

隨著工業的發展，各種氣體包括易燃易爆、有毒氣體的種類和應用范圍都得到增加，傳統的氣體泄漏檢測方法，如壓差法、氣泡法等，有其局限性，不僅操作復雜，對技術人員要求較高，而且不具有實時性。迫切需要各種方法簡單，準確性可靠的檢測方法。本文介紹了一種氣體泄漏超聲檢測系統,在分析小孔氣體泄漏產生超聲波的原理的基礎上,闡述了該檢測系統的原理及設計方案。該系統能對各種壓力容器的孔隙泄漏所產生的微弱超聲信號進行精確檢測。該系統利用技術對泄漏所產生的超聲波信號進行分析處理和聲壓級計算,從而實現對泄漏的檢測及泄漏量的估算。通過超聲波檢測，正確地判斷和定位產生泄漏位置，對于提高企業的生產效率，節約能源，確保安全具有重大意義。
    在通過對超聲波性質的研究中，我們發現超聲波是一種高頻短波，并且它在空氣中傳播具有很強的方向性。基于此特性，我設計了一套超聲波檢測電路，該電路包括了模擬電路與數字電路，其中模擬電路包含了信號放大電路和音頻處理電路；數字電路由單片機和LCD、鍵盤等外圍設備組成。在對超聲波信號的處理的過程中，信號經過放大濾波以后，一路交給單片機處理，并在顯示屏上讀出信號的強度與流速；另一路通過降頻轉化為可聽聲，從而實現檢測的目的。

關鍵詞：單片機 ；聲壓級； 本底噪聲； 泄漏超聲波

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