Magnetic suspension apparatus

Magnetic bearing apparatus for suspending a rotary member for rotation about a reference axis defined by a fixed member comprising:

• a first magnetically permeable core means carried by said fixed member and including at least one pair of axially spaced cylindrical core members defining at least four circular pole pieces radially spaced from said axis and each of said cylindrical core members including a radially extending flange portion,
• a second magnetically permeable core means carried by said rotary member including a cylindrical base core member and at least three core walls extending radially therefrom and terminating in at least four circular pole pieces adjacent to and collinear with the pole pieces of said pair of cylindrical core members, whereby to provide at least four axially successive, circular magnetically permeable gaps adapted to conduct magnetic flux lines of force generally parallel to said reference axis,
• permanent magnet means coupled between said flange portions of said first core means for producing a fixed magnetic flux of one polarity across the first and fourth of said successive gaps and of the opposite polarity across the second and third of said successive gaps whereby said magnetic flux inherently produces stabilizing forces in the radial direction and oppose relative radial movement of said rotary member relative to said reference axis and simultaneously to produce destabilizing forces in the axial direction from a predetermined neutral force position,
• at least one pair of annular electric coils, one supported on each of said cylindrical core members and adapted upon energization to produce variable magnitude fluxes of one polarity across said first and second gaps and simultaneously of the opposite polarity across said third and fourth gaps,
• electrical sensor means coupled between said rotary member and said fixed member for providing a signal proportional relative axial movements thereof from said predetermined neutral force position, and
• amplifier means responsive to said signal for supplying control currents to said coils of a magnitude and sense to reduce said sensor signal to zero and thereby stabilize said axial magnetic forces,
• each of said pole pieces including circular lands and grooves for concentrating said flux lines across said gaps at said lands whereby to increase said radial stabilizing forces, and further including closed electrically conductive rings in said grooves for providing eddy current damping of said radial movement between said members.

Magnetic suspension apparatus for suspending one member relative to another, one of said members being fixed and the other being movable relative thereto in at least first and second orthogonal, translational directions comprising,

• a first magnetically permeable core means carried by one of said members and a second magnetically permeable core means carried by the other of said members, said first and second core means having cooperative pole pieces and so relatively shaped and juxtaposed as to define at least four successive magnetically permeable gaps therebetween adapted to conduct magnetic flux lines of force generally parallel to the first of said translational directions,
• permanent magnet means carried by one of said core means for producing a constant magnetic flux of one polarity across said first and fourth gaps and of the opposite polarity across said second and third gaps whereby the resultant magnetic forces acting between said core poles tend to oppose relative movement of said members in the second of said translational directions and simultaneously to produce unstable relative movement of said members in the first of said directions,
• at least a pair of electromagnetic means also carried by said one core means adapted when energized to produce variable magnitude electromagnetic fluxes of one polarity across said first and second gaps and simultaneously of the opposite polarity across said third and fourth gaps,
• means responsive to relative movement between said members in said first direction for energizing said electromagnetic means in accordance with such movement whereby to produce resultant magnetic forces between said core poles in a direction and magnitude to reduce said movement in said first direction to zero and thereby to stabilize said members in said first direction, and mechanical back-up bearing means carried by one of said relatively movable members and spaced from the other of said members in both said translational directions for limiting said relative movement of said movable member upon failure of said magnetic bearing suspension.