US4918346A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low ripple-torque permanent magnet brushless motor
Assignee: Hitachi Ltd
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Filing: 1988-06-24
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Granted: 1990-04-17
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Expires: 2008-06-24
Abstract
Abstract The stator comprises three phase driving coils and an electric commutator for controlling current to the driving coils. The rotor comprises permanent magnets which are alternately magnetized in N polarity and S polarity. Driving torque is generated corresponding to the current flowing through the driving coils and the permanent magnets. On the surface of the permanent magnet facing to the driving coils, two non-magnetizing portions are provided in each permanent magnet having either N or S polarity.
Inventors
- 👤 Fumio Tajima
- 👤 Nicolas Samman
- 👤 Kunio Miyashita
- 👤 Hiroshi Katayama
- 👤 Motoya Ito
- 👤 Seiichi Narushima
- 👤 Kiyoshi Yamamuro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:44
CPC Classifications
H; H02; H02K; H02K1/00; H02K1/06; H02K1/22; H02K1/27; H02K1/2793; H02K1/2795; H02K29/00; H02K29/06; H02K29/08
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
80 words
A permanent magnet brushless motor comprising permanent magnets which are magnetized in N polarity and S polarity alternately in equal intervals, three phase driving coils facing the permanent magnets, electric commutators for controlling current to the driving coils, wherein a driving torque is generated corresponding to the current flowing through the driving coils and the permanent magnet, characterized in that two non-magnetizing regions are disposed on a surface of each permanent magnet having one polarity and facing said driving coils.
Claim 2
Dependent Claim
80 words
A permanent magnet brushless motor comprising permanent magnets which are magnetized in N polarity and S polarity alternately in equal intervals, three phase driving coils facing the permanent magnets, electric commutators for controlling current to the driving coils, wherein a driving torque is generated corresponding to the current flowing through the driving coils and the permanent magnet, characterized in that two non-magnetizing regions are disposed on a surface of each permanent magnet having one polarity and facing said driving coils.
Claim 3
Dependent Claim
36 words
A permanent magnet brushless motor according to claim 1, wherein said permanent mgnet is in a shape of a disk, and said non-magnetizing portion is a slot extending from an outer peripheral portion of the disk.
Claim 4
Dependent Claim
29 words
A permanent magnet brushless motor according to claim 1, wherein said non-magnetizing portion is wider toward an outer peripheral portion from an inner peripheral portion of said permanent magnet.
Claim 5
Dependent Claim
54 words
A permanent magnet brushless motor according to claim 1, wherein said permanent magnet is in a shape of a disk, and when a diameter of said permanent magnet is D m , a width of said driving coil is W, and pole numbers are P, the coil width W is selected to be ##EQU3##
Claim 6
Dependent Claim
38 words
A permanent magnet according to claim 1, wherein, when an area of said non-magnetizing portion is Am, and an area of said permanent magnet is Sm, said permanent magnet and said non-magnetizing portion are formed to be 0.08<Am/Sm<0.25.
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) | 1993-04-16 | 1993-10-16 | 1994-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-16 | 1997-10-16 | 1998-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-16 | 2001-10-16 | 2002-04-17 | $7700.00 | Window Closed / Lapsed |