US3783313A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical stepping motors having low inertia rotors
Assignee: Canadian Patents and Development Ltd
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Filing: 1972-06-29
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Granted: 1974-01-01
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Expires: 1992-06-29
Abstract
Abstract The stepping rate of a multi-phase electrical stepping motor is increased by pairing stator sections with a rotor disc carrying two sets of axially extending rotor poles. Embodiments having four sections and a rotor of two discs, carrying segmental strip rotor poles, has stator poles of segmental opposed form aligned across an annular ring slot opening in the outer torus wall. Another embodiment has an annular pole slot in the torus side and angularly staggered salient poles, cooperating with a ring rotor of crenulate form with arcuate segmental pole faces joined by oblique bridge portions. All sections may be active sections, or an end section may have permanent magnet excitation of stator poles which number is the count of all active poles, and the rotor pole set associated has a like number of poles, to lock the rotor in each step position; a winding energized by low DC current is poled to cancel holding flux, a magnetic shunt being provided to avoid magnet demagnetization.
Inventors
- 👤 R Mathur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:55
CPC Classifications
H; H02; H02K; H02K37/00; H02K37/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
169 words
An electrical stepping motor having stator sections coaxial of and spaced along an axis, each section having the form of a hollow torus shell, an annular disc wall of the torus having an annular coaxial slot opening and the slot being widened radially at intervals to define sectoral elements comprising sets of stator poles, one set of stator poles extending radially inwardly and a set extending radially outwardly, each set terminating at said slot opening and having arcuate pole faces, the sets of pole faces being in angularly staggered relation, an electrical winding in each torus energizeable to magnetize said stator poles, a rotor shaft rotatable about said axis, support elements mounted on said shaft, and rotor poles carried by said support elements comprising a crenulate ferromagnetic rotor ring disposed concentrically in said slot opening corrugated in the radial direction and comprising arcuate segments forming sets of rotor poles having alternately inward-facing and outward-facing cylindrical pole surfaces, consecutive segmental portions of said ring being connected by oblique bridging members.
Claim 2
Dependent Claim
169 words
An electrical stepping motor having stator sections coaxial of and spaced along an axis, each section having the form of a hollow torus shell, an annular disc wall of the torus having an annular coaxial slot opening and the slot being widened radially at intervals to define sectoral elements comprising sets of stator poles, one set of stator poles extending radially inwardly and a set extending radially outwardly, each set terminating at said slot opening and having arcuate pole faces, the sets of pole faces being in angularly staggered relation, an electrical winding in each torus energizeable to magnetize said stator poles, a rotor shaft rotatable about said axis, support elements mounted on said shaft, and rotor poles carried by said support elements comprising a crenulate ferromagnetic rotor ring disposed concentrically in said slot opening corrugated in the radial direction and comprising arcuate segments forming sets of rotor poles having alternately inward-facing and outward-facing cylindrical pole surfaces, consecutive segmental portions of said ring being connected by oblique bridging members.
Claim 3
Dependent Claim
174 words
The motor of claim 1 wherein one of the stator sections is a detenting section and wherein a side wall of the torus remote from said slot comprises a non-magnetic annulus, said torus comprising a thick annular ring permanent magnet diSposed adjacent said non-magnetic annulus and fitted contiguously within the outer and inner cylindrical walls of the torus and providing a holding flux in said slot between registered stator and rotor detenting poles, a magnetic shunt annulus spaced adjacent said magnet on the side of the slot opening and having a radial reluctance gap, the number of stator poles and rotor poles of the detenting section each being n.(M-1) where n is the number of poles of an active stator section and where (M-1) is the number of active stator sections of a motor having a total of M stator sections, said torus having a winding disposed between said shunt annulus and said slot opening energizeable to cancel the holding flux developed by said permanent magnet across said slot opening to release the rotor.
Claim 4
Dependent Claim
46 words
The motor of claim 1 wherein the axial length of the rotor ring is approximately equal to the axial length of a stator pole face and wherein each rotor pole face has a circumferential length slightly less than the circumferential length of a stator pole face.
Claim 5
Dependent Claim
26 words
The motor of claim 3 wherein the radial thickness of the rotor ring is a half or less of the radial span of the slot opening.
Claim 6
Dependent Claim
28 words
The motor of claim 1 wherein the stator sections disposed between two consecutive axially-spaced rotor pole support discs have their contiguous torus walls comprised as a single annulus.
Claim 7
Dependent Claim
38 words
The motor of claim 5 wherein the motor has a single sleeve housing and each torus has a cylindrical outer wall engaging said sleeve, said sleeve being secured in fixed angular relation thereto and to said single annulus.
Claim 8
Dependent Claim
31 words
The motor of claim 1 wherein the rotor rings are carried on laterally projecting supports integral with the disc periphery received under the inner faces of the outwardly facing rotor segments.
Claim 9
Dependent Claim
37 words
The motor claimed in claim 7 wherein each rotor disc has its periphery crenulated and carries a single rotor ring having an axial length sufficient to span the stator pole faces of two adjacent opposed stator sections.
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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |