US3937533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Axially and radially controllable magnetic bearing
Assignee: National Aeronautics and Space Administration
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Filing: 1974-02-08
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Granted: 1976-02-10
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Expires: 1994-02-08
Abstract
Abstract An axially controllable magnetic bearing apparatus provides radial stiffness force control between a rotor and stator. The bearing includes a pair of axially spaced air gaps defined by corresponding pairs of annular pole pieces of the rotor and stator. Permanent magnets carried by the rotor generate constant axial bias fluxes in each of the air gaps. A pair of coils, disposed to axially excite the air gaps with variable flux, are driven in a manner so that the sum of the total fluxes in each of the air gaps is varied to change the radial stiffness between the bearing rotor and stator. Axial force between the rotor and stator is produced by exciting the two coils to vary the difference of the total air gap fluxes. The pair of coils are driven in a bridge circuit by pulse-width modulated signals. The radial stiffness force of the bearing is varied in response to a control system for radially damping the bearing rotor and/or for shifting the vibrational resources of the bearing to avoid a vibrational resonance condition.
Inventors
- 👤 Leo Veillette
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:33
CPC Classifications
F; F16; F16C; F16C32/00; F16C32/04; F16C32/0406; F16C32/044; F16C32/0444; F16C32/0457; F16C32/0459; F16C32/0468; F16C32/0474; F16C32/0476; H; H02; H02K; H02K7/00; H02K7/08; H02K7/09
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
99 words
An axially servoable magnetic bearing having a controllable radial stiffness comprising: a bearing rotor having a pair of axially spaced, axially facing annular pole pieces; a bearing stator generally coaxially disposed with respect to the rotor, said stator having a corresponding pair of axially spaced, axially facing, annular pole pieces, each stator pole piece facing an opposite corresponding one of the rotor pole pieces so as to define first and second axially spaced annular axial are gaps between the rotor and stator; and controllable magnetic flux generating means for independently varying magnetic flux through each of the two airgaps.
Claim 2
Dependent Claim
99 words
An axially servoable magnetic bearing having a controllable radial stiffness comprising: a bearing rotor having a pair of axially spaced, axially facing annular pole pieces; a bearing stator generally coaxially disposed with respect to the rotor, said stator having a corresponding pair of axially spaced, axially facing, annular pole pieces, each stator pole piece facing an opposite corresponding one of the rotor pole pieces so as to define first and second axially spaced annular axial are gaps between the rotor and stator; and controllable magnetic flux generating means for independently varying magnetic flux through each of the two airgaps.
Claim 3
Dependent Claim
54 words
The apparatus of claim 1 in combination with control means for exciting the flux generating means in a manner for varying the sum of the total fluxes in the two air gaps in order to vary the radial stiffness and for varying the difference in the total fluxes for axially shifting the bearing rotor.
Claim 4
Dependent Claim
36 words
The apparatus of claim 2 wherein the flux generating means comprises a pair of axially spaced coils coaxial with the rotor, each coil positioned to produce flux in a corresponding one of the two air gaps.
Claim 5
Dependent Claim
24 words
The apparatus of claim 3 where the flux generating means includes means for generating constant bias fluxes through each of the two air gaps.
Claim 6
Dependent Claim
34 words
The apparatus of claim 4 wherein the means for generating constant bias fluxes includes an additional pair of annular axial air gaps defined by additional corresponding annular pole pieces of the rotor and stator.
Claim 7
Dependent Claim
33 words
The apparatus of claim 3 wherein the first and second coils are excited by coil currents, the control means including means for exciting the two coils with pulse width modulated current pulse trains.
Claim 8
Dependent Claim
60 words
The apparatus of claim 6 wherein the first and second coils each have a pair of terminals, one of each pair being connected together to form three terminals for the two coils, the means for exciting the two coils with pulse-width modulated current pulse trains including means for exciting the three driving terminals with three synchronous overlapping voltage pulse trains.
Claim 9
Dependent Claim
48 words
The apparatus of claim 7 wherein the control means is responsive to an axial signal and a radial signal and includes means for generating a triangular wave signal and means for comparing the radial signal and the axial signal with the instantaneous amplitude of the triangular wave signal.
Claim 10
Dependent Claim
47 words
The apparatus of claim 8 wherein the control means includes means for generating a second triangular wave signal inverted from the first mentioned triangular wave signal and means for comparing the radial signal and the axial signal with the instantaneous amplitude of the second triangular wave signal.
Claim 11
Dependent Claim
31 words
The apparatus of claim 1 in combination with means for sensing the angular velocity of the rotor and means for varying the radial stiffness in response to the sensed angular velocity.
Claim 12
Dependent Claim
23 words
The apparatus of claim 1 in combination with means for sensing the radial eccentricity of the bearing rotor response to the sensed eccentricity.
Claim 13
Dependent Claim
154 words
An axially servoable magnetic bearing having a controllable radial stiffness comprising: a bearing rotor having four axially spaced annular pole pieces and a radially facing annular pole piece; a bearing stator generally coaxially disposed with respect to the rotor, said stator having corresponding four axially spaced, axially facing pole pieces, a radially facing annular pole piece, each stator pole piece facing an opposed corresponding one of the rotor pole pieces so as to define four axially spaced annular gaps and a radial gap between the rotor and stator; coil means for exciting in series the radial gap and a first of the axial gaps; coil means for exciting in series the radial gap and a second of the axial gaps; permanent magnetic means for constantly exciting in series the first and a third of the gaps; and permanent magnetic means for constantly exciting in series the second and a fourth of the axial gaps.
Claim 14
Dependent Claim
154 words
An axially servoable magnetic bearing having a controllable radial stiffness comprising: a bearing rotor having four axially spaced annular pole pieces and a radially facing annular pole piece; a bearing stator generally coaxially disposed with respect to the rotor, said stator having corresponding four axially spaced, axially facing pole pieces, a radially facing annular pole piece, each stator pole piece facing an opposed corresponding one of the rotor pole pieces so as to define four axially spaced annular gaps and a radial gap between the rotor and stator; coil means for exciting in series the radial gap and a first of the axial gaps; coil means for exciting in series the radial gap and a second of the axial gaps; permanent magnetic means for constantly exciting in series the first and a third of the gaps; and permanent magnetic means for constantly exciting in series the second and a fourth of the axial gaps.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-09 | 1979-08-11 | 1980-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-09 | 1983-08-11 | 1984-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-09 | 1987-08-11 | 1988-02-10 | $7700.00 | Window Closed / Lapsed |