| The existing non-contact piezoelectric motors can be mainly divided into liquid medium transmission and gas medium transmission by sound field according to the difference of the force transmission medium between the stator and the runner.The operation stability of these two types of motors is relatively poor,and the control of medium is more difficult.Therefore,it is necessary to explore more stable operation and easy-to-control power transmission media to promote the development and progress of the non-contact piezoelectric motors.The existing piezoelectric motors modulated by electromagnetical field are mainly of rotary type,and the motion is relatively simple.The electromagnetically modulated non-contact linear piezoelectric motor is proposed in paper.It not only solves the problems of friction and wear between the stator and runner,as well as the stability and control difficulty of the power transmission medium,but also enriches and expands the structure and motion form of the electromagnetically modulated non-contact piezoelectric motor.The following several respects are researched of this linear piezoelectric motor in paper:The motor drive principle is designed and conceived,and the structure model of the motor is determined according to the drive principle.The calculation equation of the magnification ratio of the flexible magnification mechanism is established,and the influence of the mechanism parameters on the magnification ratio is analyzed.The tensile and bending stiffness of single-sided circular arc and straight beam hinges are calculated and analyzed respectively.The results show that the influence of the angle θ of the magnifying mechanism on the magnification ratio is much greater than the influence of the rod length on the magnification ratio.The tensile and bending stiffness of the single-sided arc flexible hinge is much greater than that of the straight beam-shaped flexible hinge.And the stiffness of both hinges decreases with the increase of hinge length,and increases with the increase of thickness.The overall stiffness of the flexible amplifying mechanism is strongly dependent on the straight beam hinge.According to Maxwell’s electromagnetic formula,the horizontal force equation of the electromagnetic modulation mechanism is established,and the change law of the horizontal static electromagnetic force and dynamic electromagnetic force under the influence of air gap,relative displacement between teeth and the number of turns is analyzed.The results show that: With the increase of the number of turns and the current,the electromagnetic force gradually increases.As the relative displacement between teeth increases,the electromagnetic force first increases and then decreases.When the displacement reaches a tooth pitch,the electromagnetic force is zero.The free vibration equations of piezoelectric stack,AB beam,HG beam and IJ beam are established respectively.According to the continuity and displacement boundary conditions between the components,the first 6-order natural frequencies of the piezoelectric motor are solved.The influence of changes in the thickness and length of the motor’s flexible hinge,the length of the magnification mechanism and other parameters on the natural frequency is also analyzed.The results show that: the first-order natural frequency of the motor is about 20 Hz.As the structural parameters of the motor change,the influence on the first-order natural frequency of the motor is greater than the second-order natural frequency.The forced vibration equations of piezoelectric stack,AB beam,HG beam and IJ beam are established respectively.According to Duhamel’s integral,the forced response of each component under the excitation of sawtooth wave is solved and analyzed.The results show that the end displacement of the IJ beam is greater than 200 μm under the low frequency drive of the piezoelectric drive mechanism.Under the excitation of sawtooth wave,the piezoelectric drive mechanism can effectively reduce the influence of inertia on the motor,and can well meet the design requirements.According to theoretical research,the prototype design parameters were determined,and the experimental prototype was processed and assembled.Set up an experiment to debug the prototype.The magnification ratio of the flexible magnification mechanism,the natural frequency and the output characteristics of the prototype are tested and analyzed respectively,which verifies the correctness of the theoretical analysis. |
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