Research On Single Driving Foot Ultrasonic Motor Using Longitudinal-Bending Modal

The ultrasonic motor which developed in recent decades is a kind of newspecial micro motor,with large torque at low speed,high torque density,fast response,no electromagnetic noise,good electromagnetic compatibility(EMC),resistance to low temperature vacuum and suitable for space environment,etc.The ultrasonic motor mainly uses the inverse piezoelectric effect of piezoelectric material(PZT),changing theintroduced electrical energy into the mechanical energyneeded for the output,then output the power and drive the load.Thesis proposes a new type of singledrive foot ultrasonic motor using longitudinalbending modal,and connect the poling directionand circuit of the piezoelectric vibrator.The singledrive foot ultrasonic motorusing longitudinal_bending modal is drived by longitudinal vibration of piezoelectric vibrator and bending vibration of piezoelectric vibrator.It mainly used the two modes of piezoelectric materials,respectively,d33 modeand d31 mode,the two kinds of vibration state for the ultrasonic motor to realize the longitudinal vibration and bending vibration.Thus realize the drive foot to move in ellipse trajectory.Thesis mainly aims ateach part of the structure of the ultrasonic motor and carry the finite element analysis.The paper select exponential type ultrasonic horn for the structure of the horn,proposed the expression of the length of the horn.The paper established thefinite element model of the driver,and separately load the simple harmonic vibration from the X axis and Y axis direction in driving the loading area.Then output responses to the five particles in the driving surface.Thesis makes the sensitivity analyses for the ten structure parameters of the singledrive foot ultrasonic motor using longitudinal_bending modal.They are: length L1 of the horn,base length L2,the thickness tp of piezoelectric vibrators,the thickness L3 of the ring flange,the length L4 of the rear end cover,the piezoelectric vibrators and the ring flange and the the rear end cover has the same cross sectional dimensions: width A2,thickess B2;the width q1 of the driver foot,the width variation coefficient of the horn,the thickess variation coefficient.And get the impacts different parameters have on the longitudinal vibration mode and bending vibration mode and the influence of frequency difference of the motor,and merge the longitudinal and the bending,thus getthe ideal structural parameters.This chaptermakes analyses for the vibratility of the singledrive foot ultrasonic motor using longitudinal_bending modal,using resonance responseanalyses to get the displacement-frequency curvefrom the X axis and Y axis direction in driving foot and further optimize the structure parameters,and obtain the displacement-time curvefrom the X axis and Y axis direction in driving foot via transient analysis,thus get the motion curve of the driving foot.Thesis establishes the contact model of the longitudinal bending composite ultrasonic motor with single driving foot.Analysis of the driving foot trajectory,the tangential motion and normal motion.Through the analysis of the contact force between the driving foot and moving obtained the expression of pre pressure on the contact angle and the contact Angle of the expression which the friction layer implemented the driving foot.Through the analysis of the contact force between the driving foot and rotor,obtaining the expression of friction under various contact angles.Through the analysis of the stress of the rotor,obtaining the size of the load in different contact angles,and expressions of the load and power.Through the number simulation ofthe contact model of ultrasonic motor,obtaining the relationship between the contact angle and pre pressure,load and contact angle,load and speed,load and longitudinal bending amplitude,load and the friction material,the output power and speed,and draw the corresponding curve.