Title page for ETD etd-2421171249711311

Type of Document Dissertation
Author Thompson, Swen
URN etd-2421171249711311
Title Analysis of the Dynamic Interferences between the Stator and Rotor of a Refrigeration Compressor Motor
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
West, Robert L. Jr.
Wicks, Alfred L.
Mitchiner, Reginald G. Committee Chair
  • air gapeccentricity
  • finite element analysis
  • electric motor
  • Refrigeration compressor
  • stator/rotor interference
  • unbalanced magnetic pull
Date of Defense 1997-07-05
Availability unrestricted
This thesis involves the development and study of a finite element model of a hermetic, single-vane compressor and a single-phase alternating current induction motor assembled in a common housing. The manufacturer of this unit is experiencing a high scrap rate due to interference during operation between the stator and rotor of the motor. The rotor shaft of the motor is non-typical because of its cantilever design. The finite element model was first subjected to eigenvalue analysis. This revealed that the interference producing displacements were not the result of torque application to the rotor at a frequency close to an eigenvalue of the mechanical system. After a review of the literature and discussions with Electrical Engineering Department faculty possessing extensive motor experience, it was surmised that the physical phenomenon causing the rotor displacement was unbalanced magnetic pull. This phenomenon occurs in the air gap of rotating electric machines due to eccentricity in the air gap.

The model was then subjected to simultaneous harmonic force inputs with magnitudes of unity on the rotor and stator surfaces to simulate the presence of unbalanced magnetic pull. It was found that the rotor shaft acts as a cantilever beam while the stator and housing are essentially rigid. The displacements due to these forces were examined and then scaled to develop the motor parameters necessary to produce the radial forces required for stator/rotor interference. Several recommendations were then made regarding possible solutions to the interference problem.

  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  etd.pdf 636.07 Kb 00:02:56 00:01:30 00:01:19 00:00:39 00:00:03

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.