US4751415A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless DC motor with means for compensating ripple torque
Assignee: Panasonic Holdings Corp
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Filing: 1987-04-28
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Granted: 1988-06-14
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Expires: 2007-04-28
Abstract
Abstract A brushless DC motor comprising a stator with plural exciting windings and a rotor made of a permanent magnet is provided with a compensation winding wound in the stator and compensation magnetic poles disposed on the rotor such that a torque which is generated between the compensation winding and the compensation magnetic poles of the rotor may eliminate fluctuation of the torque generated by interaction of the exciting windings of the stator and the main magnet of the rotor.
Inventors
- 👤 Teruaki Kitamori
- 👤 Sotoo Asano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:29
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/08
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
88 words
A brushless DC motor for compensating ripple torque, comprising: a stator having exciting windings, a rotor having main magnetic poles opposing said exciting windings across an air gap, compensation magnetic poles disposed completely about the periphery of said rotor, and a compensation winding, opposing across said air gap said compensation magnetic poles disposed on said rotor, for generating a compensating torque having inverse phase and an identical cyclic period with respect to a variation of torque generated by interaction of said exciting windings and said main magnetic poles.
Claim 2
Dependent Claim
88 words
A brushless DC motor for compensating ripple torque, comprising: a stator having exciting windings, a rotor having main magnetic poles opposing said exciting windings across an air gap, compensation magnetic poles disposed completely about the periphery of said rotor, and a compensation winding, opposing across said air gap said compensation magnetic poles disposed on said rotor, for generating a compensating torque having inverse phase and an identical cyclic period with respect to a variation of torque generated by interaction of said exciting windings and said main magnetic poles.
Claim 3
Dependent Claim
75 words
A brushless DC motor for compensating ripple torque in accordance with claim 1, wherein the ratio of ampere turns of said compensation winding to that of said exciting windings is selected to be 1/2 of a difference between a maximum generating torque due to said exciting windings and a special minimum torque generated by switching of current due to interaction of the main magnetic poles of said rotor and said exciting windings of said stator.
Claim 4
Dependent Claim
51 words
A brushless DC motor for compensating ripple torque in accordance with claim 1, wherein main magnets having said main magnetic poles and compensation magnets having said compensation magnetic poles of the rotor are disposed on a shaft so that the magnetic poles thereof are parallel to an axis of the shaft.
Claim 5
Dependent Claim
31 words
A brushless DC motor for compensating ripple torque in accordance with claim 3, wherein said main magnets and compensation magnets of the rotor are magnetized in one piece of magnetic substance.
Claim 6
Dependent Claim
47 words
A brushless DC motor for compensating ripple torque in accordance with claim 3, wherein said main magnets and compensating magnets are formed so that a resultant magnetizing pattern generating a magnetic field of said main magnets and compensating magnets is magnetized in one piece of magnetic substance.
References Cited (Backward Citations)
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Cited
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Cited
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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) | 1991-06-14 | 1991-12-14 | 1992-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-14 | 1995-12-14 | 1996-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-14 | 1999-12-14 | 2000-06-14 | $7700.00 | Window Closed / Lapsed |