New breakthrough in ultrasonic motor technology in China
Ultrasonic motors are a new concept of micro-motors that developed rapidly in the 1980s. It is the crystallization of the development and synthesis of vibration and wave science, materials science, power electronics, automatic control and super-precision. It breaks through the concept of traditional motor, has good electromagnetic compatibility, low noise, and can be vacuumed. Working at high and low temperatures, the shape is diversified, and the efficiency does not decrease as the size decreases.
The key issues that need to be solved in the industrialization of ultrasonic motor technology in China are: the preparation technology of piezoelectric materials; the nonlinear characteristics of ultrasonic motors; the manufacturing technology of ultrasonic motors. This project is a study of manufacturing technology. The TRUM-60 ultrasonic motor is a traveling wave rotary ultrasonic motor, and a single bearing support additional alignment structure is proposed.
The traveling wave type rotary ultrasonic motor is called ultrasonic motor (USM). It is the earliest development of ultrasonic motor, the most mature technology, and the industrialization and engineering application are also successful. Since the frequency of the stator vibration exceeds 20 kHz, which belongs to the ultrasonic frequency band, it is often referred to as an ultrasonic motor or an ultrasonic motor. Due to its special principle and structure, ultrasonic motor has many outstanding features compared with electromagnetic motor, such as: no magnetic field interference, self-locking power failure, fast response, large thrust/weight ratio, simple structure, flexible form and so on. Therefore, as an actuator of the control system has a wide application prospect, has been applied to precision positioning and other aspects. However, with the development of high technology, the application system puts forward higher requirements on the control precision of the motion process. Improving the speed stability is a necessary condition for the ultrasonic motor to be widely used in the precision control system.
The speed stability of the traveling wave type ultrasonic motor is closely related to the contact interface between the stator and the rotor. Published in "Journal of China Electrical Engineering", October 29, 2011, "Study on the Velocity Stability of Traveling Wave Rotary Ultrasonic Motors", a method for improving speed stability through structural optimization design is proposed.
In order to improve the speed stability of the traveling wave type rotating ultrasonic motor, the paper analyzes the influence of machining and assembly error on the speed stability under the existing double bearing support. It is considered that the uneven pressure along the circumference is one of the main causes of speed fluctuation. A single bearing support additional alignment structure is proposed to achieve pressure self-balancing at the contact interface. Theoretical and experimental analysis shows that this solution makes the pressure distribution at the contact interface more uniform and the velocity stability is better. Compared with the original structure, the results show that the ultrasonic motor's no-load speed fluctuation rate is reduced by about 40.0% and the fluctuation range is less than 2.0% under the condition that the main performance indexes such as the output torque and speed range of the ultrasonic motor are basically the same.
In order to gain a foothold in the industrialization of ultrasonic motor, the team of Academician Zhao Yusheng of Nanjing University of Aeronautics and Astronautics established its own Wama Ultrasonic Motor Company, which created a good platform for rapidly transforming advanced scientific research results into productivity.