摘要

科学地解决能源三气的计量问题，一直是业界困扰的问题。进入二十一世纪以来，用于测量气体流量的超声波流量计以其无压损、无阻力、量程比宽、受流体限制少等优点受到业界的广泛关注。随着国内人民生活水平的提高，科技不断地进步，控制不断地完善，从而促使超声波技术在气体流量检测系统领域占据主导权，也使得气体流量测量仪被广泛应用。在超声波设计领域中，气体流量检测技术成为目前一处亮丽的风景线，因为其开发资源众多，开发经验丰富，最重要的是成本较低，控制在用户可承受的范围内，使用超声波的方式搭建气体流量检测系统，气体流量测量仪逐渐成为世界各国关注的重点。

软件程序上选用KeilC语言编写，主要包括初始化配置模块、脉冲发射模块、数据采集模块、流速及流量计算模块、LCD驱动及显示模块等。完成硬件电路的设计、焊接和软件程序的编写，进行系统的整机调试，对实际中出现误差的可能性做具体的分析。

本文主要介绍气体流量测量仪的设计，首先介绍超声波检测的基本原理以及其发展历史、目前现状等。然后对设计中的数字式气体流量测量仪的总体设计及各功能模块进行了探讨，确定了气体流量测量仪设计的解决方案并对系统解决方案中的主控芯片和可编程逻辑控制芯片进行了选型。之后重点研究数字化气体流量测量仪系统的硬件设计，包括超声波的发射电路，接收电路，信号调理电路以及数据采集处理系统的设计和实现。最后介绍了气体流量测量仪系统的软件设计，对系统软件设计的总体流程、超声波激励脉冲信号产生、数据采集系统的逻辑控制以及回波信号的数据处理进行了介绍。

关键词：超声波气体流量计；单片机；LCD，数据采集

Abstract

It has always been a perplexing problem for the industry to solve the measurement problem of energy three gases scientifically. Since the beginning of the 21st century, ultrasonic flowmeter used to measure gas flow has been widely concerned by the industry for its advantages of no pressure loss, no resistance, wide range ratio and less fluid restriction. With the improvement of the living standard of the domestic people, the continuous progress of science and technology, and the continuous improvement of control, so as to promote the ultrasonic technology in the field of gas flow detection system occupy the dominant right, but also make the gas flow measurement instrument is widely used. In the field of ultrasonic design, gas flow detection technology has become a beautiful landscape at present, because of its development resources, rich experience, the most important is the low cost, control in the user's affordable range, the use of ultrasonic way to build gas flow detection system, gas flow measurement instrument has gradually become the focus of the world.

The software program is written in KeilC language, including initial configuration module, pulse transmission module, data acquisition module, flow rate and flow calculation module, LCD driver and display module. Complete the hardware circuit design, welding and software program writing, the system debugging, the actual error of the possibility to do a specific analysis.

This paper mainly introduces the design of gas flow measuring instrument, first introduces the basic principle of ultrasonic detection and its development history, current situation and so on. Then the overall design and functional modules of the digital gas flow measuring instrument in the design are discussed, and the design solutions of the gas flow measuring instrument are determined and the main control chip and programmable logic control chip in the system solution are selected. Then focus on the digital gas flow measuring instrument system hardware design, including ultrasonic transmission circuit, receiving circuit, signal conditioning circuit and data acquisition and processing system design and implementation. Finally, the software design of gas flow measuring instrument system is introduced, and the overall process of system software design, the generation of ultrasonic excitation pulse signal, the logic control of data acquisition system and the data processing of echo signal are introduced.

Keywords: Ultrasonic gas flowmeter; Single chip microcomputer; LCD, data acquisition

目录

摘要............................................................................................................................. I

Abstract................................................................................................................... III

第一章 绪论............................................................................................................. 1

1.1引言............................................................................................................. 1

1.2研究目的与意义........................................................................................ 2

1.3国内外研究现状........................................................................................ 3

1.4课题研究内容及章节安排........................................................................ 5

第二章 超声波检测基本原理及方法................................................................... 7

2.1超声波的定义及基本性质........................................................................ 7

2.1.1超声波定义及特点......................................................................... 7

2.1.2超声波的速度及波长.................................................................... 7

2.1.3超声波的衰减................................................................................. 8

2.2超声换能器................................................................................................. 8

2.2.1超声换能器的定义......................................................................... 8

2.2.2超声换能器的主要性能参数........................................................ 8

2.3流量测量原理及方法................................................................................ 9

2.3.1测量原理......................................................................................... 9

2.3.2测量方法......................................................................................... 9

2.4机械振动与超声波.................................................................................. 10

2.4.1超声场的基本物理量和超声波波型......................................... 10

2.4.2金属探伤中的超声波波型.......................................................... 11

2.5超声场及介质的声参量.......................................................................... 12

2.5.1描述超声场的物理量.................................................................. 12

2.5.2介质的声参量............................................................................... 13

第三章 系统硬件设计.......................................................................................... 14

3.1系统硬件整体结构框图.......................................................................... 14

3.2主控制器设计.......................................................................................... 15

3.2.1芯片介绍....................................................................................... 15

3.2.2时钟电路设计............................................................................... 17

3.2.3复位电路设计............................................................................... 18

3.3超声波控制电路...................................................................................... 19

3.3.1超声波传感器............................................................................... 19

3.3.2超声波电路设计........................................................................... 20

3.4激励电路设计.......................................................................................... 20

3.5A/D转换电路设计................................................................................... 21

3.5.1 A/D 转换器的选择...................................................................... 21

3.5.2 ADC0832 的介绍........................................................................ 21

3.5.3 单片机对 ADC0832 的控制原理的介绍............................... 22

3.6显示电路设计......................................................................................... 23

第四章 系统软件部分设计.................................................................................. 25

4.1主程序流程图.......................................................................................... 25

4.2主程序流程图.......................................................................................... 26

第五章 系统仿真调试部分.................................................................................. 28

5.1  软件研发的背景................................................................................... 28

5.2  软件程序设计....................................................................................... 28

5.3  基于Proteus电路图绘制.................................................................... 29

第六章 结束语....................................................................................................... 31

参考文献................................................................................................................. 32

致谢.......................................................................................................................... 34