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US4547758A
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Cylindrical permanent magnet and method of manufacturing
Assignee: Proterial Ltd
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Filing: 1982-12-02
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Granted: 1985-10-15
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Expires: 2002-12-02
Abstract
Abstract A cylindrical permanent magnet suitable for use as the rotor magnet of a stepping motor. The magnet is a sintered cylindrical permanent magnet having a composition expressed by MO.nFe 2 O 3 , where M represents Ba, Sr, Pb or mixture thereof, while n represents a value of 5 to 6. The sintered cylindrical permanent magnet is provided on its surface with multipolar anisotropy of more than 8 (eight) magnetic poles. Disclosed also is a method of producing the cylindrical permanent magnet.
Inventors
- 👤 Motoharu Shimizu
- 👤 Noriyuki Noda
- 👤 Yoshihiro Noguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:39
CPC Classifications
H; H01; H01F; H01F7/00; H01F7/02; H01F7/0205; H01F7/021; H01F41/00; H01F41/02; H01F41/0253; H01F41/0273; H01F41/028; Y; Y10; Y10S; Y10S264/00; Y10S264/58
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
116 words
A cylindrical permanent magnet, comprising: a sintered material having a composition expressed by MO.nFe 2 O 3 , where M represents Ba, Sr, Pb or a mixture thereof, and n is a value of 5 to 6, the magnet being characterized by a surface multipolar anisotropy of more than eight poles imparted to the cylindrical portion of the magnet, and the magnet being further characterized by having an inside diameter D 1 and an outside diameter D 2 of the cylindrical portion which satisfy the condition: D.sub.1 /D.sub.2 =1-K.sub.1 π/P where P is the number of poles imparted to the cylindrical portion of the magnet, and K 1 is a constant defined by 1.5≦K 1 ≦2.5.
Claim 2
Dependent Claim
116 words
A cylindrical permanent magnet, comprising: a sintered material having a composition expressed by MO.nFe 2 O 3 , where M represents Ba, Sr, Pb or a mixture thereof, and n is a value of 5 to 6, the magnet being characterized by a surface multipolar anisotropy of more than eight poles imparted to the cylindrical portion of the magnet, and the magnet being further characterized by having an inside diameter D 1 and an outside diameter D 2 of the cylindrical portion which satisfy the condition: D.sub.1 /D.sub.2 =1-K.sub.1 π/P where P is the number of poles imparted to the cylindrical portion of the magnet, and K 1 is a constant defined by 1.5≦K 1 ≦2.5.
Claim 3
Dependent Claim
14 words
A cylindrical permanent magnet according to claim 1 wherein D 1 /D 2 ≧0.65.
Claim 4
Independent Claim
76 words
A method of producing a cylindrical permanent magnet comprising the steps of forming a cylindrical green body from a material consisting essentially of MO.nFe 2 O 3 , where M represents Ba, Sr or Pb and n being a value of 5 to 6, and containing 14 to 20% of water, subjecting the green body to multi-polar magnetic fields to impart a surface multipolar anisotropy of more than 8 (eight) poles, and then sintering the body.
Claim 5
Independent Claim
76 words
A method of producing a cylindrical permanent magnet comprising the steps of forming a cylindrical green body from a material consisting essentially of MO.nFe 2 O 3 , where M represents Ba, Sr or Pb and n being a value of 5 to 6, and containing 14 to 20% of water, subjecting the green body to multi-polar magnetic fields to impart a surface multipolar anisotropy of more than 8 (eight) poles, and then sintering the body.
Claim 6
Dependent Claim
69 words
A method of producing a cylindrical permanent magnet according to claim 3, wherein the inside diameter D 1 and the outside diameter D 2 of the cylindrical portion of the sintered body are selected to meet the following condition: D.sub.1 /D.sub.2 =1-K.sub.1 π/P where, K 1 representing a constant value not smaller than 1.5, said sintered body being magnetized at its surface to develop a multiplicity of magnetic poles.
Claim 7
Dependent Claim
28 words
A method of producing a cylindrical permanent magnet according to claim 4, wherein said constant value K 1 is selected to meet the condition of 1.5≦K 1 ≦2.5.
References Cited (Backward Citations)
US3114715A
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US4057606A
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JPS5674907A
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JPS5737803A
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JPS57128909A
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JPS57130407A
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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) | 1988-10-14 | 1989-04-15 | 1989-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-14 | 1993-04-15 | 1993-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-14 | 1997-04-15 | 1997-10-15 | $7700.00 | Window Closed / Lapsed |