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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