US4873462A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stepping motor with low detent torque
Assignee: EASTERN AIR DEVICES Inc ONE PROGRESS DRIVE DOVER NH 03820 A CORP OF
•
Filing: 1988-09-16
•
Granted: 1989-10-10
•
Expires: 2008-09-16
Abstract
Abstract A synchronous motor having peripheral teeth on the rotor magnetized by a permanent magnet and radially inwardly projecting, electromagnetically energized stator teeth. The rotor teeth and stator teeth are skewed relative to each other. The annular arc length subtended by the skew as projected on the cylindrical peripheral envelope of the rotor teeth equals the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four. Each of the rotor teeth projects upon two adjacent stator teeth, and/or each of the stator teeth projects upon two adjacent rotor teeth.
Inventors
- 👤 Timothy J. Harned
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:13
CPC Classifications
H; H02; H02K; H02K21/00; H02K21/12; H02K21/14; H02K21/20; H02K37/00; H02K37/10; H02K37/12; H02K37/14; H02K37/18; H02K2201/00; H02K2201/06
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
168 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the rotor teeth each projecting radially upon two stator teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
Claim 2
Dependent Claim
168 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the rotor teeth each projecting radially upon two stator teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
Claim 3
Dependent Claim
18 words
A motor according to claim 1, wherein one of said pluralities of teeth extends parallel to said axis.
Claim 4
Dependent Claim
25 words
A motor according to claim 2, wherein the rotor teeth are skewed relative to said axis and the stator teeth extend parallel to said axis.
Claim 5
Dependent Claim
25 words
A motor according to claim 2, wherein the stator teeth are skewed relative to said axis and the rotor teeth extend parallel to said axis.
Claim 6
Dependent Claim
18 words
A motor according to claim 1, wherein the rotor and stator teeth are skewed relative to the axis.
Claim 7
Dependent Claim
57 words
A motor according to claim 1, wherein said cylindrical portion includes two axially displaced segments each having a plurality of said rotor teeth, the teeth of said segments being oppositely magnetized by said magnetic field and the teeth of one segment being angularly displaced by one half tooth pitch relative to the teeth of the other segment.
Claim 8
Dependent Claim
18 words
A motor according to claim 6, wherein one of said pluralities of teeth extends parallel to said axis.
Claim 9
Dependent Claim
25 words
A motor according to claim 6, wherein the rotor teeth are skewed relative to said axis and the stator teeth extend parallel to said axis.
Claim 10
Dependent Claim
25 words
A motor according to claim 6, wherein the stator teeth are skewed relative to said axis and the rotor teeth extend parallel to said axis.
Claim 11
Dependent Claim
18 words
A motor according to claim 6, wherein the rotor and stator teeth are skewed relative to the axis.
Claim 12
Dependent Claim
17 words
A motor according to claim 1, wherein the stator teeth each project radially upon two rotor teeth.
Claim 13
Dependent Claim
17 words
A motor according to claim 6, wherein the stator teeth each project radially upon two rotor teeth.
Claim 14
Dependent Claim
11 words
A motor according to claim 1, wherein said integer is four.
Claim 15
Dependent Claim
17 words
A motor according to claim 1, wherein said permanent magnet means is mounted on the rotor assembly.
Claim 16
Dependent Claim
17 words
A motor according to claim 6, wherein said permanent magnet means is mounted on the rotor assembly.
Claim 17
Dependent Claim
168 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the stator teeth each projecting radially upon two rotor teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
Claim 18
Dependent Claim
168 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the stator teeth each projecting radially upon two rotor teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
Claim 19
Dependent Claim
208 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion including two axially displaced segments each having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the stator teeth each projecting radially upon two rotor teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the teeth of said segments being oppositely magnetized by said magnetic field and the teeth of one segment being angularly displaced by one half tooth pitch relative to the teeth of the other segment, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
Claim 20
Dependent Claim
208 words
A synchronous motor comprising, in combination, a rotor assembly including a cylindrical portion having an axis, said portion including two axially displaced segments each having a plurality of annularly spaced rotor teeth projecting radially to a cylindrical peripheral envelope on said axis, a stator assembly coaxial with said rotor assembly and having a plurality of radially projecting stator poles, said poles each having a plurality of stator teeth projecting radially toward said envelope, the stator teeth each projecting radially upon two rotor teeth, means for electrically energizing said stator poles, permanent magnet means in one of said assemblies for establishing a magnetic field at said rotor teeth, said rotor teeth and stator teeth each extending longitudinally along the stator poles and rotor portion, the teeth of said segments being oppositely magnetized by said magnetic field and the teeth of one segment being angularly displaced by one half tooth pitch relative to the teeth of the other segment, the plurality of rotor teeth and stator teeth being skewed relative to each other, the annular arc length subtended by the skew as projected on said envelope being substantially equal to the arc length corresponding to the angular pitch of the rotor teeth divided by an integer between two and four.
References Cited (Backward Citations)
US2589999A
Cited
US2982872A
Cited
US3343014A
Cited
US4025810A
Cited
US4112319A
Cited
US4385250A
Cited
US4424463A
Cited
US4516048A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-09 | 1993-04-10 | 1993-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-09 | 1997-04-10 | 1997-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-09 | 2001-04-10 | 2001-10-10 | $7700.00 | Window Closed / Lapsed |