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Title: Dynamically stable magnetic suspension/bearing system

Abstract

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finitemore » range of those displacements. 32 figs.« less

Inventors:
Publication Date:
Research Org.:
University of California
OSTI Identifier:
201521
Patent Number(s):
US 5,495,221/A/
Application Number:
PAN: 8-207,622
Assignee:
Univ. of California, Oakland, CA (United States) PTO; SCA: 420200; PA: EDB-96:054727; SN: 96001551762
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 27 Feb 1996
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; MAGNETIC BEARINGS; DESIGN; STABILIZATION; ROTATION; FORCING FUNCTIONS; LEVITATION

Citation Formats

Post, R.F. Dynamically stable magnetic suspension/bearing system. United States: N. p., 1996. Web.
Post, R.F. Dynamically stable magnetic suspension/bearing system. United States.
Post, R.F. 1996. "Dynamically stable magnetic suspension/bearing system". United States. doi:.
@article{osti_201521,
title = {Dynamically stable magnetic suspension/bearing system},
author = {Post, R.F.},
abstractNote = {A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1996,
month = 2
}
  • A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by usemore » of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.« less
  • An independent wheel suspension system is described for a vehicle having an engine adapted to provide a driving torque, a chassis, vehicle support means for resiliently supporting the chassis for displacement relative to a driving surface, and a wheel assembly for each wheel having a vertical center plane through the center thereof and a wheel axis substantially perpendicular to the vertical center plane. The wheel assembly has a chamber angle relative to the vertical center plane adapted to undergo a change of chamber as the wheel assembly undergoes movement relative to the vertical center plane. The independent wheel suspension systemmore » comprises: differential means comprising a differential housing, a differential input at an engine end of the differential housing adapted to be coupled to the engine so as to receive the driving torque therefrom about a differential input axis. The differential housing has a pair of lateral sides on opposite sides of the differential input axis, each lateral side having a differential output axis therethrough. The differential means is adapted to redirect the driving torque from the differential input axis to the differential output axis and is supported by the vehicle support means to position the differential input axis substantially perpendicular to the wheel axis.« less
  • An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficultmore » mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.« less
  • Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.
  • Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.