3.2 ultrasonic motor
Ultrasonic motors (USM) use the inverse piezoelectric effect of piezoelectric materials to cause micro-mechanical vibrations (vibration frequencies above 20 kHz) in the ultrasonic frequency band, through the stator and rotor (or mover) The friction between the stator converts the microscopic vibration of the stator into a macroscopic one-way rotation (or linear motion) of the rotor (or mover). It breaks the concept of the traditional motor that obtains the rotational speed and torque by the electromagnetic effect, and it is also a remarkable new technology in the development of the micro-motor technology.
Compared to conventional motors, ultrasonic motors have a number of advantages:
(1) The structure is simple, and it is composed of two basic components: a vibrating component and a moving component;
(2) The torque per unit volume is 10 times that of the conventional motor of the same volume;
(3) The low speed performance is good, the speed can be adjusted to zero, and the large torque can be directly output at low speed;
(4) The braking torque is large and no additional brake is required;
(5) The mechanical time constant is small and the fast performance is good;
(6) There is no magnetic field and electric field, no electromagnetic interference and electromagnetic noise.
At present, many ultrasonic motors have been commercialized in many countries in foreign countries such as Japan. New products for ultrasonic motors from Canon, Panasonic, and Hitachi have been used in advanced cameras, camcorders, and optical instruments. The development direction of ultrasonic motor technology is to further improve efficiency.
Ultrasonic motors use a new principle and structure, do not need magnets and coils, but use the inverse piezoelectric effect of piezoelectric materials and ultrasonic vibration to directly obtain motion and force (moment). It breaks the concept of a motor that has so far obtained rotational speed and torque from electromagnetic effects, and is a high-tech at the forefront of current world science. Due to the ultrasonic, the motor has many features that electromagnetic motors do not have. Although its invention and development has only 20 years of history, it has been successfully applied in the fields of aerospace, robotics, automobiles, precision positioning, medical equipment, and micro-machinery. .
