US4499420A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Disk type motor speed detecting device
Assignee: SINANO DENKI A CORP OF JAPAN KK
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Filing: 1982-02-03
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Granted: 1985-02-12
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Expires: 2002-02-03
Abstract
Abstract A disk type motor speed detecting device is made up of a doughnut shaped plate high in magnetic permeability secured to the inner surface of the lower plate of the body, a coil wound on a small portion of the doughnut shaped plate; a doughnut shaped magnet with S and N poles one of which has a magnetization angle of more than 180°, a disk-shaped yoke secured to the magnet, and a rotary shaft adapted to rotate the magnet relative to the doughnut shaped plate.
Inventors
- 👤 Manabu Shiraki
- 👤 Akihiro Nakajima
- 👤 Takashi Miyazawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:57
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/46; G01P3/465
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
149 words
A disk type motor speed detecting device comprising: a motor speed detecting device body having upper and lower plates; a doughnut shaped plate made of a material high in magnetic permeability secured to the inner surface of said lower plate; a coil which is wound on a portion of said doughnut shaped plate in toroidal manner; a doughnut shaped magnet confronted with said doughnut shaped plate with a relatively small space therebetween, said doughnut shaped magnet having angular S and N poles one of which has a magnetization angle of more than 180°; a disk-shaped yoke which is fixedly placed on the upper surface of said doughnut shaped magnet, said disk-shaped yoke being made of a material high in magnetic permeability; and a rotary shaft which penetrates a substantially central portion of said doughnut shaped magnet and is rotatably supported by said upper and lower plates of said body.
Claim 2
Dependent Claim
149 words
A disk type motor speed detecting device comprising: a motor speed detecting device body having upper and lower plates; a doughnut shaped plate made of a material high in magnetic permeability secured to the inner surface of said lower plate; a coil which is wound on a portion of said doughnut shaped plate in toroidal manner; a doughnut shaped magnet confronted with said doughnut shaped plate with a relatively small space therebetween, said doughnut shaped magnet having angular S and N poles one of which has a magnetization angle of more than 180°; a disk-shaped yoke which is fixedly placed on the upper surface of said doughnut shaped magnet, said disk-shaped yoke being made of a material high in magnetic permeability; and a rotary shaft which penetrates a substantially central portion of said doughnut shaped magnet and is rotatably supported by said upper and lower plates of said body.
Claim 3
Dependent Claim
21 words
A device as claimed in claim 1, in which said doughnut shaped plate is made up of at least two segments.
Claim 4
Dependent Claim
24 words
A device as claimed in claim 1, in which said doughnut shaped plate has a portion bent downwardly on which said coil is wound.
Claim 5
Dependent Claim
27 words
A device as claimed in claim 1, in which said doughnut shaped magnet is madeup of two segments which are magnetized into S and N poles, respectively.
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) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |