Levitation And Experimental Research Of Motor Rotor Based On The Ultrasonic Levitation Support

Ultrasonic levitation technology is a method of using high frequency vibration to complete the near-field suspension of objects.Its characteristic is that the gas film is loaded with no contact suspension.In this way,the suspension bearing is constructed and the structure is simpler.Based on the theory of mechanical design,ultrasound,and piezoelectric,the paper combined with the national natural science fund project “Design theory and method research of high speed motor based on ultrasonic levitation support(project number : 50977037)”,the national high technology research and development program(863 Program)“Development and research of vertical drive piezoelectric feeder "(Project Number : 2006AA042225)”,and put forward the new idea of using ultrasonic axial suspension to support rotor of motor rotor is proposed for the first time.The paper design and dynamic analysis of the structure of the suspended support motor rotor support.Then,according to the structure of the axial suspension supporting motor rotor,this paper designs the vibration source of the conical radiation terminal piezoelectric transducer,and base on the method of wearing the same cone bearing as the cone angle on both ends of the motor shaft,this paper completes the structure design of ultrasonic suspended high speed motor and experiment research.Follows are the major research content of this paper :1.This paper determines the type of piezoelectric transducer by the motor rotor support,discusses the basic vibration mode of piezoelectric vibrator.And analyzes on the related performance parameters of the energy conversion process.On this basis,the electromechanical equivalent model of piezoelectric ultrasonic transducer is established,and discusses the factors of affect the effective emission power of transducer.2.Through the research on the mechanism of ultrasonic near-field suspension,the sound radiation model of ultrasonic levitation support and the film suspension model of gas extruding are established.On the basis of the theoretical calculation and finite element analysis,detailed analyzes the relationship of the suspended clearance and the bearing capacity.The dynamic pressure changes within the suspended clearance isobtained by transient analysis of the model of the gas extrusion membrane suspension,and the levitation force time average is got by the periodic average processing method.Based on analytical derivation and numerical calculation,obtains the effect regularity of ultrasonic levitation ability by the equivalent extrusion parameters and vibration amplitude ratio.Analyzed the mechanical effects such as gas film stiffness and damping clearance with ultrasonic vibration.This paper designs and studies on the support structure of the ultrasonic levitation motor rotor has a theoretical basis.3.Based on experiments and finite element method,the radiating surface of cone type piezoelectric transducer resonant frequency and vibration modal are tested and analyzed in this paper.According to test the suspension of the different quality bearing cap,and obtains the relationship between the suspension clearance and load of the support structure.Under the condition of ultrasonic levitation support,theory analyzes on suspension clearance changes on the critical speed of the motor rotor and the influence of the vibration modal.4.This paper designs the structure suspension support of the motor rotor.And the structure of the suspension bearing by the cone angle 66 ° of the radiation end face and the cone angle of the same metal bearing cap.Through the bearing gas film reached no-contact suspension,researches on the suspension mechanism of the bearing gas film.And dynamic analyzes the structure of gas film by the finite element analysis method.5.According to the suspension mechanism,the paper designs and manufactures the axial support structure of ultrasonic suspension high-speed motor,and experimental tests the motor speed and suspension clearance.The research shows that the cone-shaped radiated end surface piezoelectric transducer as the vibration source,and cone bearing cap make up the suspension bearing,the structure realizes the non-contact suspension of the rotor of the high speed motor.Smaller suspended clearance,larger amplitude,and the stable bearing gas film is helpful to improve the stability of the motor under high speed,At the same time,the smaller the suspended clearance,bearing capacity is larger,the greater the gas film stiffness.