Micromotor, the full name "micromotor", refers to a motor with a diameter of less than 160mm or a rated power of less than 750mW. Micromotors are commonly used in control systems or transmission mechanical loads to perform functions such as detection, resolution, amplification, execution or conversion of electromechanical signals or energy.
Conventional-sized motors are dominated by various electromagnetic motors, as well as hydraulic and pneumatic motors. Miniaturizing the motor can be done in two ways. One is the small and medium-sized motor that drives the principle and structure of its own and is miniaturized. Such as the current use of disk drives, cameras, electric toys and stepper motors and DC motors in office automation machines. The other is to develop new drive principles with new functional materials and make micromotors of various types. Such as piezoelectric ultrasonic motors, electrostatic motors, and word micro-actuators developed using shape memory alloys, giant magnetostrictive devices, stacked piezoelectric vibrators, artificial muscle tendons, and the like.
In the fields of micro-robot, precision engineering, aerospace and other applications, micro-motors have both dual functions of drive and precision control. The drive can be linear, rotary or multi-degree of freedom; the control target can be position, speed or force (torque). ). Therefore, from the application point of view, the micro-motor should meet the following basic requirements: under the premise of small size and light weight, it can generate a large amount of motion displacement, and output a large power, low power consumption, high control precision, fast response. . This is also a fundamental feature that distinguishes micromotors from conventional conventional motors and other microactuators. Meeting the above requirements and achieving a specific structural or functional goal is a common problem that must be solved in the design and development of micro-motors.
The miniaturization of the motor brings difficulties to manufacturing and assembly, but it also brings unprecedented benefits. For example, it is possible to use a special material which is difficult to consider due to factors such as cost of a large-sized motor; a profiled material such as a film or a block is easily prepared, and the like. Because of this, the structure and types of micro-motors are extremely rich. At present, the main types of micro-motors have appeared: electrostatic, electromagnetic, giant magnetostrictive, piezoelectric, shape memory alloy. Among them, the electrostatic and electromagnetic rotor/stator is non-contact driven, the shape memory alloy is direct drive, the piezoelectric and giant magnetostrictive are contact drive, and have a holding force. [1]
Piezoelectric materials are ideal for making micromotors. Because the piezoelectric material can be deformed by itself only by applying an electric field. Piezoelectric films can be obtained in a number of ways, and are conveniently fabricated into tiny active structures. There are three ways to make a drive from a piezoelectric material:
1. Using the deformation of the piezoelectric material itself, working under a very small stroke (below micrometers);
2, the application of the principle of leverage or combined with the elastomer into a composite structure (such as: bimorph, Lanjiewen vibrator), to expand the deformation of the piezoelectric material itself (several hundred microns or less);
3. The deformation of the piezoelectric ceramics is managed to extend indefinitely. There are three main types of ultrasonic motors that use resonance to generate traveling or standing waves.
A peristaltic motor that synthesizes a box structure, an inertial motor that utilizes the inertia stop/slip principle.
