US3777196A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low-inertia synchronous inductor motor
Assignee: Sigma Instruments Inc
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Filing: 1972-10-20
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Granted: 1973-12-04
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Expires: 1992-10-20
Abstract
Abstract The rotor structure of a synchronous inductor motor, such as a stepping motor, is of a compact, low-inertia and high-magnetic efficiency construction wherein a relatively thin axiallymagnetized annular washer is fixed intermediate the wholly planar end surfaces of relatively lightweight back-to-back cup-shaped pole pieces and extends radially from a relatively large central shaft fully to the roots of the pole-piece teeth.
Inventors
- 👤 J Field
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:44
CPC Classifications
H; H02; H02K; H02K37/00; H02K37/10; H02K37/12; H02K37/14; H02K37/18; H02K21/00; H02K21/12; H02K21/14; H02K21/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
200 words
An electrical synchronous inductor motor having a rotor structure including a shaft having fixed thereon at least one permanent magnet and a pair of toothed rotor pole pieces of magnetic material associated respectively with the poles of said magnet, and an electromagnetically-excited internally-toothed stator structure closely surrounding said rotor structure, said permanent magnet consisting of a thin, substantially annular washer having a lesser axial than radial thickness and permanently magnetized in the axial direction thereof, at least one of said rotor pole pieces being of substantially cup-shaped hollow form, and each of said pole pieces having teeth extending axially along a substantially cylindrical outer periphery thereof and having a substantially planar end surface in abutting relation to a different axial end of said washer magnet, said planar end surface of said cup-shaped pole piece being on the outside of the closed bottom thereof and the rim of said cupshaped pole piece being axially spaced from said washer magnet, said pole pieces having no axially-overhanging relation to said washer magnet therebetween, and said washer magnet extending radially from said shaft substantially to said teeth of said pole pieces, and means securing said washer magnet and pole pieces in said abutting relation.
Claim 2
Dependent Claim
200 words
An electrical synchronous inductor motor having a rotor structure including a shaft having fixed thereon at least one permanent magnet and a pair of toothed rotor pole pieces of magnetic material associated respectively with the poles of said magnet, and an electromagnetically-excited internally-toothed stator structure closely surrounding said rotor structure, said permanent magnet consisting of a thin, substantially annular washer having a lesser axial than radial thickness and permanently magnetized in the axial direction thereof, at least one of said rotor pole pieces being of substantially cup-shaped hollow form, and each of said pole pieces having teeth extending axially along a substantially cylindrical outer periphery thereof and having a substantially planar end surface in abutting relation to a different axial end of said washer magnet, said planar end surface of said cup-shaped pole piece being on the outside of the closed bottom thereof and the rim of said cupshaped pole piece being axially spaced from said washer magnet, said pole pieces having no axially-overhanging relation to said washer magnet therebetween, and said washer magnet extending radially from said shaft substantially to said teeth of said pole pieces, and means securing said washer magnet and pole pieces in said abutting relation.
Claim 3
Dependent Claim
54 words
An electrical synchronous inductor motor as set forth in claim 1 wherein both of said pole pieces are of substantially cup-shaped hollow form, and wherein said cup-shaped pole pieces are disposed in back-to-back relationship with said planar end surfaces on the outsides of the closed bottoms thereof in sandwiching relation to said washer magnet.
Claim 4
Dependent Claim
74 words
An electrical synchronous inductor motor as set forth in claim 2 wherein each of said cup-shaped rotor pole pieces has a closed bottom wall of substantially uniform axial thickness and has side walls of thicknesses diminishing in the axial direction from said closed bottom wall toward the rim thereof, and wherein the material of said magnet extends radially substantially fully between said shaft and the roots of said teeth of said rotor pole pieces.
Claim 5
Dependent Claim
73 words
An electrical synchronous inductor motor as set forth in claim 3 wherein said teeth of said rotor pole pieces are of a like radial height, from said roots to the outer periphery thereof, which is small in relation to the axial thickness of said washer magnet, and wherein twice the radial gap between oppositely disposed surfaces of stator and rotor teeth is small in relation to said axial thickness of said washer magnet.
Claim 6
Dependent Claim
28 words
An electrical synchronous inducTor motor as set forth in claim 4 wherein said permanent-magnet rotor magnet has an axial-to-radial thickness not in excess of about 1 to 3.
Claim 7
Dependent Claim
30 words
An electrical synchronous inductor motor as set forth in claim 5 wherein said securing means consists of cement bonding said rotor pole pieces and washer together and to said shaft.
Claim 8
Dependent Claim
43 words
An electrical synchronous inductor motor as set forth in claim 5 wherein the back ends of said pole pieces are wholly planar and normal to the axis of said shaft fully between said shaft and the peripheral radial extremities of the teeth thereon.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |