Patent US3671789A successfully refreshed from Google Patents.
US3671789A
Expired / Lapsed
US
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Synchronous reluctance motors having rotor segments of extended pole span
Assignee: Canadian Patents and Development Ltd
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Filing: 1971-01-19
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Granted: 1972-06-20
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Expires: 1991-01-19
Abstract
Abstract In reluctance motors having rotors with segmentally disposed, axially extended, radially laminated stacks of steel strips carried on a conducting core, improved synchronous performance and increased asynchronous torque are achieved when the rotors are modified to associate only one segmental body with each pair of adjacent MMF poles of the stator field. The modification is actually a simplification, namely the span of each segmental body is peripherally extended to nearly the span of two adjacent stator poles, whereby the steel laminae carry a higher peak magnetic flux centered on the strips lying at the radial middepth position of a stack. A higher total flux is also realized and the flux distribution in the air gap is more nearly sinusoidal, lacking the gaps characterizing flux patterns of prior art rotors. Odd-numbered harmonic coefficients of the flux distribution are thus minimized. Considerable savings in construction are also realized. Motors are described ranging from one pair of rotor poles up to four pairs, although the invention extends to any practicable higher pole numbers.
Inventors
- 👤 Robert W Menzies
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:08
CPC Classifications
H; H02; H02K; H02K1/00; H02K1/06; H02K1/22; H02K1/24; H02K1/246
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
112 words
An electric motor of the reluctance type having a wound stator member and a rotor member revolvable in said stator and spaced therefrom by an annular air-gap, said stator having a winding providing, when energized, a rotating MMF field comprising a predetermined number of pole-pairs, said rotor comprising a non-magnetic damping structure, and a number of ferro-magnetic bodies of segmental form carried by said damping structure adjacent said air gap, said number of bodies corresponding to said predetermined number of stator pole-pairs, each of said segmental bodies having a pair of direct magnetization axes intersecting said body and spanning an arc corresponding to the angular span of two consecutive MMF field poles.
Claim 2
Dependent Claim
112 words
An electric motor of the reluctance type having a wound stator member and a rotor member revolvable in said stator and spaced therefrom by an annular air-gap, said stator having a winding providing, when energized, a rotating MMF field comprising a predetermined number of pole-pairs, said rotor comprising a non-magnetic damping structure, and a number of ferro-magnetic bodies of segmental form carried by said damping structure adjacent said air gap, said number of bodies corresponding to said predetermined number of stator pole-pairs, each of said segmental bodies having a pair of direct magnetization axes intersecting said body and spanning an arc corresponding to the angular span of two consecutive MMF field poles.
Claim 3
Dependent Claim
55 words
An electric motor as claimed in claim 1, wherein said damping structure comprises conducting end discs, and integral conducting bar elements each associated with a corresponding segmental body, respectively, for joining said end discs and disposed adjacent said air-gap, each segmental body and the single bar element associated therewith being bisected by a quadrature axis.
Claim 4
Dependent Claim
14 words
An electric motor as claimed in claim 2 wherein said predetermined number is one.
Claim 5
Dependent Claim
16 words
An electric motor as claimed in claim 2 wherein said predetermined number is two or more.
Claim 6
Dependent Claim
47 words
An electric motor as claimed in claim 4 wherein said damping structure further comprises non-magnetic core structure extending axially between said end discs and being integral therewith and having lobe portions extending radially and bounded by said air gap, and wherein a quadrature axis bisects each lobe.
Claim 7
Dependent Claim
43 words
An electric motor as claimed in claim 5 wherein said core has two opposed lobes and supports two segmental bodies, each body comprising a group of radially stacked axially elongate flat sheets having high permeability along at least one dimension of the sheet.
Claim 8
Dependent Claim
60 words
An electric motor as claimed in claim 4 wherein said core has three or more equiangularly disposed lobes and has concave seating surfaces disposed between the lobes, each seating surface supporting one segmental body therein, and each body comprising a group of radially stacked axially elongate nested curved sheets having high permeability along at least one dimension of the sheet.
Claim 9
Dependent Claim
64 words
An electric motor as claimed in claim 7 wherein each said segmental body comprises a plurality of sub-stacks of curved sheets in radially stacked relation, the radii of curvature of the sheets of respective sub-stacks decreasing inversely with distance of the sub-stack from the core, and said damping structure includes conductive non-magnetic material interleaved between said sub-stacks and bonded electrically with said end discs.
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) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |