超声波机械振荡的弹性特点

超声波机械振荡的弹性特点
超声波是一种在弹性介质中的机械振荡,有两种形式:横向振荡(横波)及纵向振荡(纵波)。

在工业中应用主要采用纵向振荡。

超声波可以在气体、液体及固体中传播,其传播速度不同。

另外,它也有折射和反射现象,并且在传播过程中有衰减。

超声波在媒质中的反射、折射、衍射、散射等传播规律,与可听声波的规律并没有本质上的区别。

与可听声波比较,超声波具有许多奇异特性:传播特性──超声波的衍射本领很差,它在均匀介质中能够定向直线传播,超声波的波长越短,这一特性就越显著。

功率特性──当声音在空气中传播时,推动空气中的微粒往复振动而对微粒做功。

在相同强度下,声波的频率越高,它所具有的功率就越大。

由于超声波频率很高,所以超声波与一般声波相比,它的功率是非常大的。

空化作用──当超声波在液体中传播时,由于液体微粒的剧烈振动,会在液体内部产生小空洞。

这些小空洞迅速胀大和闭合,会使液体微粒之间发生猛烈的撞击作用,从而产生几千到上万个大气压的压强。

微粒间这种剧烈的相互作用,会使液体的温度骤然升高,从而使两种不相溶的液体(如水和油)发生乳化,并且加速溶质的溶解,加速化学反应。

这种由超声波作用在液体中所引起的各种效应称为超声波的空化作用。

Ultrasound is a mechanical oscillation in the elastic
medium, there are two kinds of forms: horizontal oscillation (shear wave) and the longitudinal oscillation (longitudinal wave). In industrial applications mainly adopts longitudinal oscillations. Ultrasonic can spread in gas, liquid and solid, the transmission speed is different. In addition, it also has the phenomenon of refraction and reflection, and in the process of transmission attenuation. Ultrasonic in the medium such as reflection, refraction, diffraction, scattering and spread rule, and the rule of audible sound waves there is essentially no difference between. Compared with audible sound waves, ultrasonic has many strange properties: propagation characteristics ──ultrasonic diffraction ability is very poor, it can directional rectilinear propagation in homogeneous medium, the ultrasound of the shorter the wavelength, this feature is more significant. Power features ──when sound in air, pushing the particles in the air reciprocating vibration particles for doing work. Under the same intensity, the higher the frequency of sound waves, it has the greater the power. Due to the ultrasonic frequency is very high, so ultrasound compared with general sound waves, its power is very big. Cavitation ──when the spread of ultrasound in liquid, due to the
liquid particle vibration, can produce small hole inside the liquid. These small hole expands rapidly and closed, can make the liquid particles between violent impact effect, generating thousands to tens of thousands of atmospheres of pressure. The intense interaction between particles, can make the liquid temperature rise sharply, so that the two don't mix liquid (water and oil) emulsification, and accelerates the dissolution of the solute, to speed up chemical reactions. This role by ultrasonic wave in the liquid caused by all kinds of effect is called ultrasonic cavitation effect.
超声波的特点:(1)超声波在传播时,方向性强,能量易于集中;(2)超声波能在各种不同媒质中传播,且可传播足够远的距离;(3)超声波与传声媒质的相互作用适中,易于携带有关传声媒质状态的信息(诊断或对传声媒质产生效应)。

Ultrasonic characteristics when: (1) ultrasonic propagation, directionality is strong, energy easy to concentrate; (2) ultrasonic can spread in a variety of different media, and can be spread far enough; (3) ultrasonic and sound transmission medium interaction is
moderate, easy to carry information about the state of sound transmission medium (diagnosis or effect on sound transmission medium).
2.超声波传感器
2. The ultrasonic sensor
超声波传感器是利用超声波的特性研制而成的传感器。

以超声波作为检测手段,必须产生超声波和接收超声波。

完成这种功能的装置就是超声波传感器,习惯上称为超声换能器,或者超声探头。

Ultrasonic sensor is made using ultrasonic characteristics to the sensor. In ultrasonic testing means, must produce and receive ultrasonic. Complete the function of device is the ultrasonic sensor, traditionally known as ultrasonic transducer, or ultrasonic probe.
超声波探头主要由压电晶片组成,既可以发射超声波,也可以接收超声波。

超声探头的核心是其塑料外套或者金属外套中的一块压电晶片。

构成晶片的材料可以有许多种。

超
声波传感器主要材料有压电晶体(电致伸缩)及镍铁铝合金(磁致伸缩)两类。

电致伸缩的材料有锆钛酸铅(pzt)等。

压电晶体组成的超声波传感器是一种可逆传感器,它可以将电能转变成机械振荡而产生超声波,同时它接收到超声波时,也能转变成电能,所以它可以分成发送器或接收器。

有的超声波传感器既作发送,也能作接收。

酿酒设备超声波传感器由发送传感器(或称波发送器)、接收传感器(或称波接收器)、控制部分与电源部分组成。

发送器传感器由发送器与使用直径为15mm左右的陶瓷振子换能器组成,换能器作用是将陶瓷振子的电振动能量转换成超能量并向空中幅射;而接收传感器由陶瓷振子换能器与放大电路组成,换能器接收波产生机械振动,将其变换成电能量,作为传感器接收器的输出,从而对发送的超进行检测。

控制部分主要对发送器发出的脉冲链频率、占空比及稀疏调制和计数及探测距离等进行控制。

Ultrasonic probe is mainly composed of piezoelectric chip, can emit ultrasonic already, also can receive the ultrasonic. The core of the ultrasonic probe is its plastic or metal jacket coat of a piezoelectric wafer. Constitutes a material can have many kinds of chips. Ultrasonic sensor main material have piezoelectric crystal (electrostrictive) and nickel iron aluminum alloy (magnetostriction) two kinds.
Electrostrictive material with lead zirconate titanate (PZT), etc. Piezoelectric ultrasonic sensor is composed of a reversible sensor, it can transform electrical energy into mechanical oscillation produced by ultrasonic, it receives the ultrasound at the same time, also can change into electricity, so it can be divided into the sender or receiver. Some ultrasonic sensors for send already, also can be received. Ultrasonic sensors sent by sensor (or wave transmitter), receives the sensor (or wave receiver), control part and power part. Sender sensor used by the sender and a diameter of 15 mm left and right sides of the ceramic vibrator transducer of transducer is used ceramic vibrator electric vibration energy conversion into energy and radiation into the air; And receiving sensor by the ceramic vibrator transducer and amplifying circuit, the transducer receives waves produce mechanical vibrations, its transformation into electric energy, the output of the receiver as a sensor, to send for testing. Control part of the main chain of the transmitter sends out pulses frequency, duty cycle and sparse modulation and counting and detection distance control.
二、超声波传感器的应用
Second, the application of ultrasonic sensors
1.超声波距离传感器技术的应用
1. The application of ultrasonic distance sensor technology
超声波传感器包括三个部分:超声换能器、处理单元和输出级。

首先处理单元对超声换能器加以电压激励,其受激后以脉冲形式发出超声波,接着超声换能器转入接受状态,处理单元对接收到的超声波脉冲进行分析,判断收到的信号是不是所发出的超声波的回声。

如果是,就测量超声波的行程时间,
根据测量吊车的时间换算为行程,除以2,即为反射超声波的物体距离。

把超声波传感器安装在合适的位置,对准被测物变化方向发射超声波,就可测量物体表面与传感器的距离。

超声波传感器有发送器和接收器,但一个超声波传感器也可具有发送和接收声波的双重作用。

超声波传感器是利用压电效应的原理将电能和超声波相互转化,即在发射超声波的时候,将电能转换,发射超声波;而在收到回波的时候,则将超声振动转换成电信号。

Ultrasonic sensor consists of three parts: ultrasonic transducer, processing unit and output level. First processing unit voltage incentive for ultrasonic transducer, its after stimulated to emit ultrasonic pulse form, then the ultrasonic transducer into an accepting state, processing unit receives the ultrasonic pulse were analyzed, and the judge received signals are emitted by the ultrasonic echo. If it is, measured ultrasonic time schedule and according to the measurement of time conversion for stroke, divided by 2, is the reflection of ultrasonic object distance. The ultrasonic sensor installed in the right position, analyte on the change direction of launch ultrasonic wave, can measure the object surface and the sensor distance. Ultrasonic sensor with
transmitter and receiver, but an ultrasonic sensor can also have a dual role of send and receive sound waves. Ultrasonic sensors is using the principle of piezoelectric effect will power and ultrasonic wave transformation, which at the time of launch ultrasonic wave, converts electrical energy to emit ultrasonic; While at the time of the received echo, ultrasonic vibration is converted into electrical signals.
2.超声波传感器在医学上的应用
2. The ultrasonic sensors for applications in medicine
超声波在医学上的应用主要是诊断疾病,它已经成为了临床医学中不可缺少的诊断方法。

超声波诊断的优点是:对受检者无痛苦、无损害、方法简便、显像清晰、诊断的准确率高等。

Application of ultrasound in medicine is to diagnose disease, it has become the indispensable diagnosis method in clinical medicine. Ultrasonic diagnostic advantage is: the client without pain, without damage, the method is simple,
clear imaging, diagnostic accuracy higher.
3.超声波传感器在测量液位的应用
3. The application of ultrasonic sensor in measuring liquid level
超声波测量液位的基本原理是:由超声探头发出的超声脉冲信号,在气体中传播,遇到空气与液体的界面后被反射,接收到回波信号后计算其超声波往返的传播时间,即可换算出距离或液位高度。

超声波测量方法有很多其它方法不可比拟的优点:(1)无任何机械传动部件,也不接触被测液体,属于非接触式测量,不怕电磁干扰,不怕酸碱等强腐蚀性液体等,因此性能稳定、可靠性高、寿命长;(2)其响应时间短可以方便的实现无滞后的实时测量。

The basic principle of ultrasonic liquid level measurement is: by the ultrasonic pulse signal from the ultrasonic probe, propagation in gas, air and liquid interface is reflected, after receive the echo signal is calculated after the ultrasonic propagation time, back and forth to convert a distance or liquid level height. There are many other
ultrasonic method of measuring incomparable advantages: (1) without any mechanical transmission parts, also not contact with liquid to be tested, belong to the non-contact measurement, not afraid of electromagnetic interference, not afraid of strong corrosive liquid such as acid and alkali, etc., so that stable performance, high reliability, long service life; (2) the short response time can easily realize the zero-lag real-time measurement.。