Ultrasonic transducers are widely used. They are divide […]
Ultrasonic transducers are widely used. They are divided into industries, agriculture, transportation, living, medical and military according to the industries they are applied to. According to the functions realized, it is divided into ultrasonic processing, ultrasonic cleaning, ultrasonic detection, detection, monitoring, telemetry, remote control, etc .; according to the working environment, it is divided into liquid, gas, living organisms, etc .; it is divided into power ultrasound, detection ultrasound, ultrasound imaging, etc. .
Piezoelectric ceramic transformer
Piezoelectric ceramic transformers use the piezoelectric effect of the polarized piezoelectric body to achieve voltage output. The input part is driven by a sinusoidal voltage signal, which causes it to vibrate through the inverse piezoelectric effect. The vibration wave is mechanically coupled to the output part through the input and output parts, and the output part generates electric charges through the positive piezoelectric effect to realize the electrical energy of the piezoelectric body. -Mechanical energy-Two transformations of electrical energy to obtain the highest output voltage at the resonant frequency of the piezoelectric transformer. Compared with electromagnetic transformers, this has a small size, light weight, high power density, high efficiency, breakdown resistance, high temperature resistance, no fear of combustion, no electromagnetic interference and electromagnetic noise, and simple structure, easy production, and easy mass production. Some areas have advantages such as being an ideal replacement component for electromagnetic transformers. These transformers are used in switching converters, notebook computers, neon lamp drivers, and more.
The ultrasonic motor uses the stator as a transducer, and uses the inverse piezoelectric effect of the piezoelectric crystal to make the motor stator at the ultrasonic frequency vibration, and then transfers energy by the friction between the stator and the rotor to drive the rotor to rotate. The ultrasonic motor has small volume, large torque, high resolution, simple structure, direct drive, no braking mechanism and no bearing mechanism. These advantages are beneficial to the miniaturization of the device. Ultrasonic motors are widely used in the fields of optical instruments, lasers, semiconductor microelectronics processes, precision machinery and instruments, robotics, medicine and biological engineering.
The mechanism of ultrasonic cleaning is to use the physical effects such as cavitation, radiation pressure, and sound flow when ultrasonic waves propagate in the cleaning solution, to mechanically peel off the dirt generated on the cleaning parts, and to promote the chemical reaction between the cleaning liquid and the dirt. React to achieve the purpose of cleaning objects. The frequency used by the ultrasonic cleaning machine can be selected from 10 to 500 kHz according to the size and purpose of the cleaning object, generally 20 to 50 kHz. With the increase of the frequency of the ultrasonic transducer, Langzhiwan oscillator, longitudinal oscillator, thickness oscillator, etc. can be used. In terms of miniaturization, there are also radial vibrations and flexural vibrations using a wafer vibrator. Ultrasonic cleaning has been widely used in various industries such as industry, agriculture, household equipment, electronics, automotive, rubber, printing, aircraft, food, hospital and medical research.
There are two types 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 piece. Due to the large acoustic resistance at the welding zone, that is, the junction of the two weldments, local high temperatures will cause the plastic to melt and complete the welding work under the action of contact pressure. Ultrasonic plastic welding can facilitate the welding of parts that cannot be welded by other welding methods. In addition, it also saves expensive mold costs for plastic products, shortens processing time, improves production efficiency, and is economical, fast and reliable.
By adding the fine abrasive with the ultrasonic processing tool to the workpiece under a certain static pressure, the same shape as the tool can be processed. During processing, the transducer needs to generate an amplitude of 15 to 40 microns at a frequency of 15 to 40 kHz. The ultrasonic tool continuously impacts the abrasive on the workpiece surface with a considerable impact force, destroys the ultrasonic radiation part, and breaks the material to achieve the purpose of removing the material. Ultrasonic processing is mainly applied to the processing of brittle and hard materials such as gems, jade, marble, agate, and cemented carbide, as well as the processing of shaped holes and fine deep holes. In addition, when adding ultrasonic transducer vibration to common cutting tools, it can also play a role in improving accuracy and efficiency.
Ultrasound to lose weight
Utilizing the cavitation effect and micromechanical vibration of the ultrasonic transducer, the excess fat cells under the human epidermis are broken and emulsified and discharged out of the body to achieve the purpose of weight loss and shaping. This is a new technology developed internationally in the 1990s. Zocchi in Italy applied ultrasonic degreasing to the bed for the first time and achieved success, setting a precedent for plastic surgery and beauty. Ultrasonic degreasing technology has developed rapidly at home and abroad.
Ultrasonic irradiation with appropriate frequency and intensity on plant seeds can increase the germination rate of seeds, reduce the rate of mold rot, promote the growth of seeds, and increase the growth rate of plants. According to data, ultrasound can increase the growth rate of some plant seeds by 2 to 3 times.
Blood Pressure Monitor
The ultrasonic transducer is used to receive the pressure of the blood vessel. When the balloon is pressurized to tightly press the blood vessel, the ultrasonic transducer cannot feel the pressure of the blood vessel because the applied pressure is higher than the vasodilation pressure. When the pressure of the blood vessel decreases to a certain value, the pressure of the two reaches an equilibrium. At this time, the ultrasonic transducer can feel the pressure of the blood vessel. This pressure is the systolic pressure of the heart. Take out the blood pressure value. The elimination of the stethoscope on the electronic sphygmomanometer can reduce the labor intensity of medical staff.
In toxic and radioactive environments, people can not work close to it and need remote control.Electric switches such as televisions, fans and electric lights need to be remotely controlled.Using ultrasonic transducers can be installed by remotely transmitting ultrasonic waves. The receiving transducer on the control system converts the acoustic signal into an electric signal to make the switch act.
In modern traffic, it is necessary to automatically monitor the traffic and counting of vehicles in order to grasp the operation of the vehicles. For example, the traffic supervision station is equipped with an ultrasonic transducer and its auxiliary equipment that can be used for both transmission and reception. When the vehicle passes, there will be an acoustic pulse return. The number of daily vehicles can be obtained by counting and accumulating. Install a dual-use transducer at the rear of the car to prevent a collision. Installing a receiving piezoelectric ultrasonic transducer on the road can also monitor the noise figure.
Ultrasonic distance measuring device is also called sound scale. It measures the time interval of pulses through a dual-use transducer. The sound scale can measure distances within 10m, and the accuracy can reach a few thousandths.
Leak detection and gas detection
For pressure systems, jet noise is caused by the pressure difference between the inside and outside of the pressure vessel at the leak. This noise spectrum is extremely wide. For non-pressure systems, an ultrasonic source can be placed in the closed system and then received from outside the closed system. Generally, the signal amplitude measured when there is no leakage is very small or absent, and the signal amplitude has a tendency to increase suddenly at the leak. Gas flow detection is also one of the important methods in chemical industry. There are many kinds of amplification for flow detection, such as float meter. However, the main advantage of using an ultrasonic transducer is that it does not hinder the flow of fluid.
Intelligent robots must realize the functions of freely walking in space and identifying objects, not only using ultrasonic transducers to measure blindness, but also to identify images. Therefore, a small ultrasonic transducer array is needed to achieve multiple functions. This aspect will become an important research topic and attract many scientists to fight for it.