ULTRASONIC MOTOR

PREPARED BY:-Kk

OUTLINE1. INTRODUCTION2. PIEZOELECTRIC NOTION3. PIEZOELCRIC MOTOR NOTION4. BASIC PRINCIPLE5. CONSTRUCTION6. TYPES7. MAJOR APPLICATION8. MERITS AND DEMERITS9. CONLUSION 10.REFERENCE

INTRODUCTION

It has been known for more than 30 years.

The first ultrasonic motor was introduce by v.v lavrinko in 1965.

Conversion of electric energy into motion by inverse piezoelectric effect.

This motor achieves high speed and drive forces,while still permitting the moving part to be positioned with high accuracy.

PIEZOELECTRIC NOTION

Piezoelectricity – generation of voltage in response of mechanical stress.

The word is derived from the Greek piezein, which means to squeeze or press.

This effect is also reversible. Deformation is only 0.1 % of the original dimension. Piezoelectric material- quartz(SiO2), barium titanate

(BaTiO3).

PIEZOELECTRIC MOTOR NOTION

Change in shape of piezoelectric material when electric field is applied.

It can be abbreviated as USM. It is driven by ultrasonic vibration of transducer. The ultrasonic vibration is transformed into output torque

(in rotary USM) or thrust (in linear USM) by the friction between the stator and the rotor (in rotary USM) or the moving part (in linear USM).

BASIC PRINCIPLE

generation of gross mechanical motion through the amplification and repetition of micro-deformations of active material.

The active material induces an orbital motion of the stator at the rotor contact points .

frictional interface between the rotor and stator rectifies the micro-motion to produce macro-motion of the ROTOR.

Working frequency-20 KHz to 10 MHz Amplitude of the actuator motion – 20 to 200nm

BASIC PRINCIPLE

•The active material excites a traveling flexural wave within the stator that leads to elliptical motion of the surface particles. •Teeth are used to enhance the speed that is associated with the propelling effect of these particles. •The rectification of the micro-motion an interface is provided by pressing the rotor on top of the stator and the frictional force between the two causes the rotor to spin.

Construction

Fundamental construction of USM

Ultrasonic motor by barth

TYPES OF ULTRASONIC MOTOR

Ultrasonic motor

Standing wave

bidirectional

unidirectional

Traveling wave

STANDING WAVE USM

Standing wave USM

Representation u( x, t) = A coskx coswt

It is also referred as vibratory coupler type or wood pecker type.

Standing wave USM

Low cost one vibration source Unidirectional High efficiency

TRAVELING WAVE USM

Superposition of multiple standing wave create a traveling wave.

Representation of travelling wave U(x ,p)= A cos(k x) cos(wt) + A

cos(k x - 90) cos (wt-90). Phase difference is 90 degree

Travelling wave USM

Requires two vibrating source Low efficiency.

BIDIRECTIONAL MOTOR

For linear motion bidirectional drives are required .

More than two actuators are used. These actuators must have some phase

difference It can be obtained by superimposing to

oscillations in a single resonator. Stator is hybrid construction consisting

of several actuators.

MAJOR APPLICATION

Camera auto focus lenses Driving fluid Watch motors and compact

paper handling. Optoelectronics area In micro surgery and sensor

scaning.

Merits Demerits Low cost High efficiency No magnetic

interference Compact size High power/weight

ratio.

Use of high frequency power supply

Less durability Drooping torque

speed characteristic.

CONCLUSION

These motors are very advantageous.

Electromagnetic interference is not there.

It is in great demand in the area automation and miniaturization.

These motors are low cost

REFERENCE

www.google.com www.yahoo.com www.slideworld.com www.pdf-searchengine.com www.ask.com http://www.americanpiezo.com/piezo

_theory/piezo_theory.pdf

THANK YOU