气介式压电超声换能器的研制及检测

发布时间：2018-05-15 01:00

本文选题：空气超声 + 超声换能器　；参考：《重庆医科大学》2015年硕士论文

【摘要】：由于换能器材料声阻抗与空气声阻抗严重失配,超声波很难在空气中传播,限制了空气超声的应用,因此超声换能器是空气超声技术的研究重点。为了提高空气中声波的传播效率,已有多种气介式超声换能器的研制方法。本文在前人研究的基础上,研制了一种模式转换型气介式压电超声换能器,试图开拓其在医疗卫生方面的应用。主要做了七个方面的研究：①了解了气介式超声换能器相关知识,设计了其基本结构,包括驱动系统和振动系统两部分。驱动系统即激励源,为换能器提供驱动功率。振动系统包括四部分：背衬、压电陶瓷晶堆、指数型变幅杆和弯曲振动圆盘。②设计换能器驱动系统并调试,包括驱动回路和反馈回路两部分。驱动部分负责激励换能器发射超声波；反馈回路采集换能器电压电流信号,通过锁相环自动跟踪换能器频率。③设计换能器振动系统,为振动系统各部分选择合适的材料,利用各部分频率方程计算其尺寸参数,.使振动系统各部分工作在同一谐振频率下,则换能器处于最佳工作状态。④将加工并制作好的换能器振动系统连接至驱动系统,调试信号源输出频率使换能器处于谐振状态,可得换能器此时谐振频率为33.3KHz。⑤检测换能器,包括压电陶瓷晶堆输出信号、振动系统输出信号、节圆检测和圆盘辐射声压检测。结果表明,换能器各部分工作状态良好。⑥使用光学纹影法检测换能器辐射声场,可见弯曲振动圆盘在驱动功率下明显增厚,未见明显声场,并对其原因做了分析。⑦从实验角度加工了弧形辐射盘,对其谐振频率和辐射声压做了检测,并与圆盘进行了对比,可发现弧形盘的振动并没有圆形盘理想。本文提出了一种理论可行、使用简便的气介式压电超声换能器,实验表明换能器可正常工作,并且能在很低的驱动功率下得到较高的辐射声压。在深入研究后,换能器将有望应用于医疗卫生领域,可以考虑用于理疗和药物渗透等领域,具有较高的应用前景。
[Abstract]:Due to the serious mismatch between the acoustic impedance of the transducer material and the acoustic impedance of the air, the ultrasonic wave is difficult to propagate in the air, which limits the application of the air ultrasonic. Therefore, the ultrasonic transducer is the research focus of the air ultrasonic technology. In order to improve the propagation efficiency of acoustic waves in air, many kinds of gas-mediated ultrasonic transducers have been developed. On the basis of previous studies, a mode conversion gas-medium piezoelectric ultrasonic transducer has been developed in this paper, in order to develop its application in medical and sanitary fields. In this paper, seven aspects of research are done: 1. The knowledge of gas-medium ultrasonic transducer is studied, and its basic structure is designed, including driving system and vibration system. The drive system is an exciting source, which provides the drive power for the transducer. The vibration system consists of four parts: back lining, piezoelectric ceramic stack, exponential horn and bending vibration disk .2 to design and debug the transducer drive system, including drive loop and feedback loop. The driving part is responsible for exciting the transducer to emit ultrasonic wave, the feedback loop collects the transducer voltage and current signal, and automatically tracks the transducer frequency by PLL .3 to design the transducer vibration system, and select suitable materials for each part of the vibration system. The dimension parameters are calculated by using the frequency equations of each part. If all parts of the vibration system are operated at the same resonant frequency, the transducer is in the best working state .4 the vibration system of the transducer is connected to the drive system, and the output frequency of the signal source is adjusted to make the transducer in the resonant state. It can be obtained that the resonant frequency of the transducer at this time is 33.3KHz.5 detection transducer, including the output signal of piezoelectric ceramic stack, the output signal of vibration system, the detection of nodal circle and the measurement of sound pressure of disk radiation. The results show that the sound field of the transducer is detected by optical schlieren method in good working condition. The bending vibration disk is thickened obviously under the driving power, but no obvious sound field is observed. At the same time, the causes are analyzed. 7 the arc radiating disk is machined from the angle of experiment. The resonance frequency and the sound pressure of the radial disk are measured and compared with the circular disc. It is found that the vibration of the arc disk is not ideal for the circular disk. In this paper, a practical and simple gas-medium piezoelectric ultrasonic transducer is proposed. The experiment shows that the transducer can work normally and can get high radiation sound pressure at very low driving power. After further study, the transducer is expected to be used in the field of medical and health care, which can be considered for physiotherapy and drug penetration, and has a higher application prospect.
【学位授予单位】：重庆医科大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB552

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