Common Applications Of Ultrasonic Transducers

The function of the ultrasonic transducer is to convert the input electrical power into mechanical power (ie, ultrasonic waves) and then transmit it out, while consuming a small part of the power itself.

Ultrasonic transducers are widely used, and they are divided into industry, agriculture, transportation, life, medical care and military according to the application industries. According to the realized functions, 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 body, etc.; according to the nature, it is divided into power ultrasonic, detection ultrasonic, ultrasonic imaging, etc. .

1. Piezoelectric ceramic transformer

Piezoelectric ceramic transformers use the piezoelectric effect of the piezoelectric body after polarization to achieve voltage output. The input part is driven by a sinusoidal voltage signal, and it vibrates 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 charge through the positive piezoelectric effect to realize the electrical energy of the piezoelectric body. - Two transformations of mechanical energy-electrical energy to obtain the highest output voltage at the resonant frequency of the piezoelectric transformer. Compared with electromagnetic transformers, this has the advantages of small size, light weight, high power density, high efficiency, breakdown resistance, high temperature resistance, not afraid of burning, no electromagnetic interference and electromagnetic noise, and simple structure, easy to make, easy to mass production, in Some areas become ideal replacement components for electromagnetic transformers and other advantages. Such transformers are used in switching converters, notebook computers, neon lamp drivers, and more.

2. Ultrasonic motor

The ultrasonic motor uses the stator as a transducer, uses the inverse piezoelectric effect of the piezoelectric crystal to make the motor stator vibrate at the ultrasonic frequency, and then transmits energy by the friction between the stator and the rotor to drive the rotor to rotate. Ultrasonic motors have small size, 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 optical instruments, lasers, semiconductor microelectronics, precision machinery and instruments, robotics, medicine and bioengineering.

3. Ultrasonic cleaning

The mechanism of ultrasonic cleaning is to use the physical effects of cavitation, radiation pressure, sound flow, etc. when the ultrasonic wave propagates in the cleaning solution, to mechanically peel off the dirt on the cleaning parts, and at the same time, it can promote the chemical generation between the cleaning solution and the dirt. reaction to achieve the purpose of cleaning the object. 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 ultrasonic transducer frequency, Langevin oscillator, longitudinal oscillator, thickness oscillator, etc. can be used. In terms of miniaturization, there are also radial vibration and bending vibration of the wafer vibrator. Ultrasonic cleaning is increasingly used in various industries, agriculture, household equipment, electronics, automotive, rubber, printing, aircraft, food, hospitals, and medical research.

4. Ultrasonic welding

Ultrasonic welding can be divided into two categories: 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 weldment. Due to the large acoustic resistance in the welding area, that is, the junction of the two weldments, a local high temperature will be generated to melt the plastic, and the welding work will be completed 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 the expensive mold fee of plastic products, shortens the processing time, improves the production efficiency, and has the characteristics of economy, speed and reliability.

5. Ultrasonic processing

The fine abrasive is applied to the workpiece with a certain static pressure together with the ultrasonic machining tool, and the same shape as the tool can be machined. 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 makes the abrasive on the surface of the workpiece continuously impact with a considerable impact force, destroying the ultrasonic radiation part, and breaking the material to achieve the purpose of removing the material. Ultrasonic processing is mainly used in the processing of brittle and hard materials such as gems, jade, marble, agate, and cemented carbide, as well as the processing of special-shaped holes and fine and deep holes. In addition, adding ultrasonic transducers to ordinary cutting tools can also play a role in improving accuracy and efficiency.

6. Ultrasonic weight loss

Using the cavitation effect and micro-mechanical vibration of the ultrasonic transducer, the excess fat cells under the human epidermis are broken, emulsified and discharged from the body, so as to achieve the purpose of losing weight and shaping. This is a new technology developed internationally in the 1990s. Italy's Zocchi used ultrasonic fat removal for the first time in bed, and achieved success, creating a precedent for plastic surgery and beauty. Ultrasonic fat removal technology has developed rapidly at home and abroad.

7. Ultrasonic breeding

Appropriate frequency and intensity of ultrasonic irradiation on plant seeds can improve the germination rate of seeds, reduce the rate of mold rot, promote the growth of seeds, and improve the growth rate of plants. According to information, ultrasound can increase the growth rate of some plant seeds by 2 to 3 times.

8. Electronic sphygmomanometer

The ultrasonic transducer is used to receive the pressure of the blood vessel. When the balloon is compressed and pressed against 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 a balance. At this time, the ultrasonic transducer can feel the pressure of the blood vessel, which is the systolic pressure of the heart. blood pressure value. The electronic sphygmomanometer can reduce the labor intensity of medical staff due to the cancellation of the stethoscope.

9. Telemetry and remote control

In toxic, radioactive and other harsh environments, people cannot work close to it, and need to be controlled remotely; electrical switches such as televisions, fans, and lights need remote control, and ultrasonic transducers can be installed to transmit ultrasonic waves from a remote location. The receiving transducer on the control system converts the acoustic signal into an electrical signal to make the switch act.

10. Traffic monitoring

In modern traffic, it is very necessary to automatically monitor the passing and counting of vehicles in order to grasp the operation of vehicles. For example, the traffic supervision station installs an ultrasonic transducer and its auxiliary equipment for both transceiver and transmission. When the vehicle passes through, an acoustic pulse returns, and the number of daily vehicles can be obtained by counting and accumulating. A dual-purpose transducer is installed at the rear of the car to prevent reverse collision accidents. Installing a receiving piezoelectric ultrasonic transducer on a road can also monitor the noise figure.

11. Ranging

Ultrasonic ranging device is also called 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.

12. Leak detection and gas detection

For the pressure system, at the leak, the jet noise is caused by the pressure difference between the inside and outside of the pressure vessel. This noise spectrum is extremely broad. For non-pressure systems, an ultrasonic source can be placed within the closed system and received from outside the closed system. Generally, the signal amplitude measured when there is no leakage is very small or no, and the signal amplitude tends to increase suddenly at the leakage point. Gas flow detection is also one of the important means in chemical industry. There are various amplifications for flow detection, such as rotameters and so on. But the main advantage of using an ultrasonic transducer is that it does not hinder the flow of the fluid.

13. Information collection

In order to realize functions such as free walking in space and recognizing objects, intelligent robots not only need to use ultrasonic transducers to measure distance and guide the blind, but also need to image recognition. Therefore, small ultrasonic transducer arrays are required to achieve multiple functions, and this aspect will become an important research topic, attracting many scientists to strive for it.