Longitudinal Bending Composite Mode Multi-dof Ultrasonic Motor

Piezoelectric ultrasonic motor is a new type of motor which developed rapidly in recent years. It is a driving device with ultrasonic vibration as the power source. It consists of the vibrator (stator) of ultrasonic vibration and the rotor which attached to stator. The stator generates ultrasonic vibration, which drives the rotor to generate rotary and linear motion by relying on the friction coupling between the rotor and the stator. The motor is characterized by that breaks through the concept of traditional electromagnetic motor, no magnetic pole windings and magnetic circuit. Instead of relying on the electromagnetic interaction to transmit energy, ultrasonic motor uses the ultrasonic vibration generated by the converse piezoelectric effect of piezoelectric material. Through the reasonable structure, the material microscopic deformation is switched to macroscopic movement of the rotor or the slider by resonance amplifier and friction coupling. In this kind of new structure of motor, instead of thousands upon thousands of copper wires, piezoelectric vibrato acts as the stator. Compared with traditional electromagnetic motors, ultrasonic motors not only have the advantages of simple structure and light weight, but also have characteristics of small inertia, fast response, good control, not affected by magnetic fields, motion accuracy, low cost etc. Especially, it has the characteristics of light weight, simple structure, high efficiency, low noise, low speed high torque and directly drive the load characteristics. The motor can reach the speed of hundreds of RPM (revolutions per minute), so that there is no need for additional gear, therefore to avoid a series of problems, such as vibration, shock, noise, low efficiency, difficult to control which are generated by transmission gear box. To mechanical rotation which dominated by lever and turbine system for hundreds of years, its appearance is a beneficial supplement, a significant breakthrough..Owing to longitudinal-flexural composite mode ultrasonic motor has characterist-ics of better controllability, higher output power, bigger torque, consistent positive inversion characteristics, low-speed stability, it is valued highly by the people at home and abroad. In this paper, the longitudinal-flexural composite mode piezoelectric ultrasonic motor is studies. On the basis of previous studies, the longitudinal-flexural composite mode ultrasonic motor with multi-DOF (multi degree of freedom) is investigated and discussed in this paper. Designing of the motor entity model, calculating and correcting the longitudinal and bending vibration frequency, designing the flange structure of the electric motor and other aspects of the system theory, these are all the research tasks of this thesis. It can provide the theoretical basis for design of the industry motor and promote the industrialization development of the motor. The main works of this thesis are given as follows:(1)Designing the longitudinal-flexural composite mode ultrasonic motor with multi-DOF and matching its entity model by means of finite element simulation.In this thesis, through finite element analysis, the model of longitudinal-flexural composite mode ultrasonic motor with multi-DOF is established accurately. The vibration model is analyzed in detail. The vibration frequency of two vibration model coupling is fond out by changing the size of the motor, the motor working frequency which can effective two vibration modes is obtained. According to these, the principle structure diagram of the longitudinal-flexural composite mode ultrasonic motor with multi-DOF is designed and the prototype motor is matching in practice.(2) Establish the equivalent circuit model of longitudinal-flexural composite mode ultrasonic motor with multi-DOF.Longitudinal flexural composite mode ultrasonic motor with multi-DOF completes multiple degree of freedom rotation of rotor through two or more vibration in a certain way combination. Setting up the equivalent circuit of multiple vibration modes motor is a kind of effective method to analysis the performances of this kind of motor. According to the actual motor structure, the electrical equivalent circuit is established, therefore the influences of various parameters of piezoelectric element which act on the operating performance are achieved by the application of model of equivalent circuit. Considering the influences of the actual motor design of motor to vibration frequency, the equivalent circuit of electrical motor is amended. The motor's vibration frequency is calculated through numerical simulation and compared with the frequency achieved by finite element analysis. This gives the method for the calculation of motor vibration frequency using equivalent circuit in the design of motor engineering.(3)Give the theoretical derivation of frequency equation of motor longitudinal flexural vibrating mode and amend the vibration frequency of motor by combining with the actual vibration mode.According to the vibration model of the motor, the theoretical derivation of vibration frequency equations of longitudinal-bending mode is given. Considering the mutual influences between actual vibration modes of motor, the effective mass is proposed. The longitudinal vibration of the motor is correct using bending vibration of motor. The bending vibration is correct using the longitudinal vibration of motor. Compare the revised values with measured values, the correct method of frequency in the design of ultrasonic motor with multi-DOF is put forward.(4) Measure the vibration mode of longitudinal-flexural composite mode ultrasonic motor with multi-DOF and design the flange structure of motor.In order to popularize industrial application of motor better, the displacement curve of flexural and longitudinal vibration is achieved by finite element analysis according to the flexural and longitudinal vibration mode of ultrasonic motor and the working mechanism. Furthermore, flange structure of the motor is designed. In addition, the vibration frequency of longitudinal-bending model before and after adding the flange plate are compared with corresponding measured values, the flange design provides a convenient for industrial applications of motor.