The function of the ultrasonic transducer is to convert the input electric power into mechanical power (that is, ultrasound) and then transfer it out, and consume a small part of the power itself.
Ultrasound transducer is widely used in industry, agriculture, transportation, life, medical treatment and military. According to the functions achieved, it can be divided into ultrasonic processing, ultrasonic cleaning, ultrasonic detection, detection, monitoring, telemetry, remote control, etc. According to the working environment, it can be divided into liquid, gas, organism, etc. According to the nature, it can be divided into power ultrasound, detection ultrasound, ultrasonic imaging, etc.
Piezoelectric Ceramic Transformer
The piezoelectric ceramic transformer uses the piezoelectric effect of the polarized piezoelectric body to realize the voltage output. The input part is driven by sinusoidal voltage signal, which generates vibration through the inverse piezoelectric effect. Vibration wave is mechanically coupled to the output part through the input and output parts. The output part generates charge through the positive piezoelectric effect, realizes the two transformations of piezoelectric energy, mechanical energy and electric energy, and achieves the highest output voltage under the resonant frequency of piezoelectric transformer. Compared with the electromagnetic transformer, it has the advantages of small size, light weight, high power density, high efficiency, breakdown resistance, high temperature resistance, no fear of combustion, no electromagnetic interference and electromagnetic noise, simple structure, easy manufacture, easy mass production, etc. It has become an ideal substitute for the electromagnetic transformer in some fields. This kind of transformer is used for switching converter, notebook computer, neon lamp driver, etc.
Ultrasonic motor
Ultrasound motor uses the stator as transducer, and makes use of the inverse piezoelectric effect of piezoelectric crystal to make the motor stator vibrate at the ultrasonic frequency. Then it transfers energy by the friction between the stator and the rotor, and drives the rotor to rotate. Ultrasound motor has the advantages of small size, large torque, high resolution, simple structure, direct drive, no brake mechanism, no bearing mechanism. These advantages are beneficial to the miniaturization of the device. Ultrasound motors are widely used in optical instruments, lasers, semiconductor microelectronics, precision machinery and instruments, robots, medicine and bioengineering.
ultrasonic cleaning
The mechanism of ultrasonic cleaning is to use the physical effects such as cavitation, radiation pressure and sound flow when ultrasonic wave propagates in the cleaning fluid to exfoliate the dirt on the cleaning parts mechanically, and to promote the chemical reaction between the cleaning fluid and the dirt, so as to achieve the purpose of cleaning the objects. According to the size and purpose of the cleaning material, the frequency of the ultrasonic cleaning machine can be selected from 10 to 500 kHz, usually 20 to 50 kHz. With the increase of frequency of ultrasonic transducer, Langzhiwan oscillator, longitudinal oscillator and thickness oscillator can be used. In the aspect of miniaturization, there are also radial and flexural vibrations of disk oscillators. Ultrasound cleaning has been widely used in various industries, such as industry, agriculture, household equipment, electronics, automobile, rubber, printing, aircraft, food, hospital and medical research.
Ultrasound welding
There are two kinds of ultrasonic welding: ultrasonic metal welding and ultrasonic plastic welding. Among them, ultrasonic plastic welding technology has been widely used. It uses the ultrasonic vibration generated by the transducer to transmit the ultrasonic vibration energy to the welding area through the upper welding parts. Because of the high acoustic resistance at the junction of the two weldments, local high temperature will occur to melt the plastics and complete the welding work under the action of contact pressure. Ultrasound plastic welding can easily weld parts that cannot be welded by other welding methods. In addition, it saves the expensive mould cost of plastic products, shortens the processing time, improves the production efficiency, and has the characteristics of economy, speed and reliability.
Ultrasound Processing
When the micro-abrasive is added to the workpiece with a certain static pressure along with the ultrasonic processing tool, the same shape as the tool can be machined. The transducer needs to produce 15-40 micron amplitude at the frequency of 15-40 kHz. The abrasive on the workpiece surface is continuously impacted by the ultrasonic tool with considerable impact force, which destroys the ultrasonic radiation part and breaks the material to achieve the purpose of material removal. Ultrasound processing is mainly applied to the processing of brittle and hard materials such as gems, jades, marbles, agates, cemented carbides, as well as the processing of special-shaped holes and fine and deep holes. In addition, adding ultrasonic transducer vibration to common cutting tools can also improve accuracy and efficiency.
Ultrasound Weight Loss
Using the cavitation effect of ultrasonic transducer and micromechanical vibration, the excess adipocytes under human epidermis are crushed and emulsified and discharged from the body to achieve the purpose of weight loss and shaping. This is a new technology developed in the 1990s. Zocch i, Italy, first used ultrasound degreasing in beds, and achieved success, pioneering plastic and cosmetic surgery. Ultrasound degreasing technology has developed rapidly at home and abroad.
The function of the ultrasonic transducer is to convert the input electric power into mechanical power (that is, ultrasound) and then transfer it out, and consume a small part of the power itself.
Ultrasound Breeding
The appropriate frequency and intensity of ultrasound irradiation on plant seeds can improve the germination rate, reduce the mildew rate, promote the growth of seeds, and increase the growth rate of plants. According to the data, ultrasound can increase the growth rate of some plant seeds by 2-3 times.
Electronic sphygmomanometer
Ultrasound transducer receives the pressure of blood vessel. When the balloon compresses the blood vessel, the pressure of blood vessel can not be felt by the ultrasonic transducer because the external pressure is higher than the diastolic pressure. When the balloon is gradually deflated and the pressure of the ultrasonic transducer on the blood vessel decreases to a certain value, the pressure of the two transducers reaches a balance, and then the pressure of blood vessel can be felt by the ultrasonic transducer. Pressure is the systolic pressure of the heart, which is indicated by the amplifier and the blood pressure is given. The electronic sphygmomanometer can reduce the labor intensity of medical staff because of the cancellation of stethoscope.
Telemetry and Telecontrol
In toxic, radioactive and other harsh environments, people can not get close to work and need remote control; TV sets, fans and electric lights and other electrical switches need remote control, can be equipped with ultrasonic transducers, through the remote transmission of ultrasound by the receiving transducer installed on the need control system to receive, the sound signal into electrical signals to make the switch operate.
Traffic monitoring
In modern traffic, it is very necessary to automatically monitor the traffic and counting of vehicles in order to grasp the operation of vehicles. If the traffic supervision station installs an ultrasonic transducer and its auxiliary equipment, when the vehicle passes, there will be a sound pulse to return, and the number of daily vehicles can be accumulated by counting. Installing a transducer for both sending and receiving at the rear of the car can prevent backing collision. The noise index can also be monitored by installing a receiving piezoelectric ultrasonic transducer on the highway.
Ultrasonic distance measurement
The ultrasonic distance measurement device is also called a sound ruler. It measures the pulse time interval through a dual-purpose transducer. The sound ruler can measure the distance within 10m, and the accuracy can reach several thousandths.
Ultrasonic Leak detection and gas detection
(Non-destroy Test NDT)
For the pressure system, the jet noise is caused by the pressure difference between the inside and outside of the pressure vessel at the leakage site. The noise spectrum is very wide. For the non-pressure system, an ultrasonic source can be placed in the closed system, and then received from the outside of the closed system. Generally, the signal amplitude measured without leakage is very small or not, and there is a sudden increase in the signal amplitude at the leakage site. Gas flow detection is also one of the important means in chemical industry. At present, there are many kinds of amplification in flow detection, such as float flowmeter. But the main advantage of using ultrasonic transducer is that it does not hinder the flow of fluid.
Information acquisition
In order to realize the functions of walking freely in space and recognizing objects, intelligent robots not only need to use ultrasonic transducer to measure distance and guide blindness, but also need image recognition. Therefore, we need a small ultrasonic transducer array to achieve a variety of functions, which will become an important research topic and attract many scientists to strive for it.
