Magnetic suspension with magnetic stiffness augmentation

Claim 2

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 by means of at least a pair of spaced magnetic bearing means, each bearing means 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 so relatively shaped and juxaposed 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, whereby all of said gaps are threaded by both constant permanent magnetic flux and variable magnitude electromagnetic flux, 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 movement in said first direction to zero and thereby to stabilize said members in said first direction, and means for modifying the energization of said electromagnetic means for producing electromagnetic flux components of said same polarity across all of said gaps whereby to augment said permanent magnet flux and thereby to augment said opposition to relative movement of said members in the second of said translational directions.

Claim 3

The magnetic suspension apparatus as set forth in claim 1 wherein said relative motion responsive means includes pick-off means having a part fixed to one of said members and a part fixed to the second of said members for providing a signal proportional to relative movement of said members in said first direction and amplifier means responsive to said signal for energizing said electromagnetic means and wherein said modifying means include means connected with said amplifier means for supplying bias signals of opposite senses to each of said electromagnetic means.

Claim 4

Bearing apparatus for suspending a rotary member for rotation about a reference axis defined by a fixed member by means of at least a pair of spaced magnetic bearings, each bearing means 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 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 opposes radial movement of said rotary member relative to said reference axis and simultaneously produces 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, whereby all of said gaps are threaded by both constant permanent magnet flux and variable magnitude electromagnetic flux, electrical sensor means coupled between said rotary member and said second member for providing a signal proportional to relative axial movements thereof from said predetermined neutral force position, 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 to stabilize said axial magnetic forces, and means connected with said amplifier means for modifying the energization of said electric coils for producing magnetic flux components of the same polarity across all of said gaps whereby to augment said radial stabilizing forces.

Claim 5

Bearing apparatus for suspending a rotary member for rotation about a reference axis defined by a fixed member by means of at least a pair of spaced magnetic bearings, each bearing means 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 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 opposes radial movement of said rotary member relative to said reference axis and simultaneously produces 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, whereby all of said gaps are threaded by both constant permanent magnet flux and variable magnitude electromagnetic flux, electrical sensor means coupled between said rotary member and said second member for providing a signal proportional to relative axial movements thereof from said predetermined neutral force position, 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 to stabilize said axial magnetic forces, and means connected with said amplifier means for modifying the energization of said electric coils for producing magnetic flux components of the same polarity across all of said gaps whereby to augment said radial stabilizing forces.

Claim 6

The magnetic bearing apparatus as set forth in claim 3 wherein said modifying means includes means supplying bias signals of opposite senses to each of said electric coils and means responsive to the rotation of said rotary member for controlling said modifying means.

Claim 7

The magnetic bearing apparatus as set forth in claim 4 wherein said last-mentioned means includes rotary speed responsive means and means responsive to a predetermined speed of said rotation of said rotating member for controlling said modifying means.

Claim 8

Bearing apparatus for suspending a rotary member for rotation about a reference axis defined by a fixed member by means of at least a pair of spaced magnetic bearings, each bearing means 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 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 tends to produce stabilizing forces in the radial direction and to oppose 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 electromagnetic coils one supported on each of said cylindrical core members and adapted upon energization 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 whereby all of said gaps are threaded by both constant permanent magnetic flux and variable magnitude electromagnetic flux, electrical sensor means coupled between said rotary member and said fixed member for providing a sensor signal porportional to relative axial movements thereof from said predetermined neutral force position, amplifier means responsive to said sensor signal for supplying control currents to said electromagnetic coils of a magnitude and sense to reduce said sensor signal to zero and thereby to stabilize said axial magnetic forces, and means connected with said amplifier means for modifying the energization of said electromagnetic coils for producing electromagnetic flux components of the same polarity across all of said gaps whereby to augment said radial stabilizing forces and including means supplying bias signals of opposite senses to each of said electromagnetic coils and means responsive to the rotation of said rotary member for controlling said modifying means, said means responsive to the rotation of said rotary member including speed responsive means and means responsive to a predetermined speed of said rotation of said rotating member for controlling said modifying means, said predetermined speed of rotation corresponding to a predetermined resonance frequency of the rotating system.

Claim 9

Bearing apparatus for suspending a rotary member for rotation about a reference axis defined by a fixed member by means of at least a pair of spaced magnetic bearings, each bearing means 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 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 tends to produce stabilizing forces in the radial direction and to oppose 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 electromagnetic coils one supported on each of said cylindrical core members and adapted upon energization 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 whereby all of said gaps are threaded by both constant permanent magnetic flux and variable magnitude electromagnetic flux, electrical sensor means coupled between said rotary member and said fixed member for providing a sensor signal porportional to relative axial movements thereof from said predetermined neutral force position, amplifier means responsive to said sensor signal for supplying control currents to said electromagnetic coils of a magnitude and sense to reduce said sensor signal to zero and thereby to stabilize said axial magnetic forces, and means connected with said amplifier means for modifying the energization of said electromagnetic coils for producing electromagnetic flux components of the same polarity across all of said gaps whereby to augment said radial stabilizing forces and including means supplying bias signals of opposite senses to each of said electromagnetic coils and means responsive to the rotation of said rotary member for controlling said modifying means, said means responsive to the rotation of said rotary member including speed responsive means and means responsive to a predetermined speed of said rotation of said rotating member for controlling said modifying means, said predetermined speed of rotation corresponding to a predetermined resonance frequency of the rotating system.