Patent US4409506A successfully refreshed from Google Patents.
US4409506A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction motor
Assignee: Hitachi Ltd
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Filing: 1981-07-27
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Granted: 1983-10-11
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Expires: 2001-07-27
Abstract
Abstract When an induction motor is speed-controlled with a variable frequency power supply including thyristor inverters, operating loss due to harmonics components is increased in a rotor of the induction motor. In order to diverge additional operating loss into an appreciable depth of the rotor to thereby suppress the increase in the operating loss, the rotor comprises a cylindrical member having a circumferential resistivity which is larger than axial and radial resistivities and circumferential permeability which is smaller than axial and radial permeabilities, and a core disposed in the cylindrical member and having an axial permeability which is smaller than circumferential and radial permeabilities.
Inventors
- 👤 Motoya Ito
- 👤 Noboru Fujimoto
- 👤 Noriyoshi Takahashi
- 👤 Masatoshi Watanabe
- 👤 Seizi Yamashita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:59
CPC Classifications
H; H02; H02K; H02K17/00; H02K15/00; H02K15/02; H02K15/021; H02K15/023; H02K1/00; H02K1/02; H02K1/06; H02K1/12; H02K1/14; H02K1/146; H02K1/148; H02K1/22; H02K1/27; H02K1/2706; H02K17/02; H02K17/16; H02K17/168; H02K2201/00; H02K2201/06
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
101 words
An induction motor comprising a stator having a stator core applied with a winding for generating a rotating magnetic field, and a rotor opposing the stator with a predetermined gap therebetween and rotating under the influence of the rotating magnetic field generated by the stator, said rotor including a core fitted to a rotor shaft and a cylindrical member covering the circumferential surface of the core, said cylindrical member being formed with a plurality of slits, each of said slits being elongated axially and extending through the cylindrical member in a radial direction thereof to the circumferential surface of said core.
Claim 2
Dependent Claim
101 words
An induction motor comprising a stator having a stator core applied with a winding for generating a rotating magnetic field, and a rotor opposing the stator with a predetermined gap therebetween and rotating under the influence of the rotating magnetic field generated by the stator, said rotor including a core fitted to a rotor shaft and a cylindrical member covering the circumferential surface of the core, said cylindrical member being formed with a plurality of slits, each of said slits being elongated axially and extending through the cylindrical member in a radial direction thereof to the circumferential surface of said core.
Claim 3
Dependent Claim
50 words
An induction motor according to claim 1, wherein said plurality of slits are formed over the entire circumferential area of said cylindrical member except at the opposite end portions extending in the axial direction, and said core is formed by a plurality of magnetic thin sheets which are laminated axially.
Claim 4
Dependent Claim
31 words
An induction motor according to claim 1, wherein said slits have irregular axial lengths and adjacent slits are spaced from each other by irregular distances in the axial and circumferential directions.
Claim 5
Dependent Claim
26 words
An induction motor according to claim 1, wherein said slits have the same axial length and are equally spaced from one another in the circumferential direction.
Claim 6
Dependent Claim
26 words
An induction motor according to claim 1, wherein said slits have the same axial length and are unequally spaced from one another in the circumferential direction.
Claim 7
Dependent Claim
58 words
An induction motor according to claim 1, wherein said slits are formed into two groups extending in the axial direction with a predetermined distance therebetween, each of said groups having a plurality of slits of the same axial length which are aligned in the circumferential direction and which are spaced equally from one another in the circumferential direction.
Claim 8
Dependent Claim
19 words
An induction motor according to claim 6, wherein said slits are extended obliquely with respect to the axial direction.
Claim 9
Dependent Claim
98 words
An induction motor according to claim 1, wherein said core is formed by a plurality of magnetic thin sheets which are laminated axially, said plurality of slits being formed over the entire circumferential area of said cylindrical member except at the opposite end portions extending in the axial direction, each of said slits having the same axial length and being spaced equally from one another in the circumferential direction, and a plurality of circumferential grooves extending in the circumferential direction and spaced equally from one another in the axial direction being provided so as to intersect said slits.
Claim 10
Dependent Claim
31 words
An induction motor according to claim 2, wherein said slits have irregular axial lengths and adjacent slits are spaced from each other by irregular distances in the axial and circumferential directions.
Claim 11
Dependent Claim
26 words
An induction motor according to claim 2, wherein said slits have the same axial length and are equally spaced from one another in the circumferential direction.
Claim 12
Dependent Claim
26 words
An induction motor according to claim 2, wherein said slits have the same axial length and are unequally spaced from one another in the circumferential direction.
Claim 13
Dependent Claim
58 words
An induction motor according to claim 2, wherein said slits are formed into two groups extending in the axial direction with a predetermined distance therebetween, each of said groups having a plurality of slits of the same axial length which are aligned in the circumferential direction and which are spaced equally from one another in the circumferential direction.
Claim 14
Dependent Claim
19 words
An induction motor according to claim 12, wherein said slits are extended obliquely with respect to the axial direction.
Claim 15
Dependent Claim
141 words
An induction motor comprising a stator having a stator core applied with a winding for generating a rotating magnetic field, and a rotor opposing the stator with a predetermined gap therebetween and rotating under the influence of the rotating magnetic field generated by the stator, said rotor including a core fitted to a rotor shaft and a cylindrical member covering the circumferential surface of the core, said cylindrical member including means for reducing eddy current loss when the induction motor is operated with a distorted alternating current, said means for reducing including a plurality of axially elongated slits formed in said cylindrical member so as to extend through said cylindrical member in a radial direction thereof to the circumferential surface of said core whereby eddy currents are diverged through said slits of said cylindrical member during operation of the induction motor.
Claim 16
Dependent Claim
141 words
An induction motor comprising a stator having a stator core applied with a winding for generating a rotating magnetic field, and a rotor opposing the stator with a predetermined gap therebetween and rotating under the influence of the rotating magnetic field generated by the stator, said rotor including a core fitted to a rotor shaft and a cylindrical member covering the circumferential surface of the core, said cylindrical member including means for reducing eddy current loss when the induction motor is operated with a distorted alternating current, said means for reducing including a plurality of axially elongated slits formed in said cylindrical member so as to extend through said cylindrical member in a radial direction thereof to the circumferential surface of said core whereby eddy currents are diverged through said slits of said cylindrical member during operation of the induction motor.
Claim 17
Dependent Claim
50 words
An induction motor according to claim 14, wherein said plurality of slits are formed over the entire circumferential area of said cylindrical member except at the opposite end portions extending in the axial direction, and said core is formed by a plurality of magnetic thin sheets which are laminated axially.
Claim 18
Dependent Claim
31 words
An induction motor according to claim 14, wherein said slits have irregular axial lengths and adjacent slits are spaced from each other by irregular distances in the axial and circumferential directions.
Claim 19
Dependent Claim
26 words
An induction motor according to claim 14, wherein said slits have the same axial length and are equally spaced from one another in the circumferential direction.
Claim 20
Dependent Claim
26 words
An induction motor according to claim 14, wherein said slits have the same axial length and are unequally spaced from one another in the circumferential direction.
Claim 21
Dependent Claim
58 words
An induction motor according to claim 14, wherein said slits are formed into two groups extending in the axial direction with a predetermined distance therebetween, each of said groups having a plurality of slits of the same axial length which are aligned in the circumferential direction and which are spaced equally from one another in the circumferential direction.
Claim 22
Dependent Claim
19 words
An induction motor according to claim 19, wherein said slits are extended obliquely with respect to the axial direction.
References Cited (Backward Citations)
DE74544C
Cited
GB183845A
Cited
GB266780A
Cited
US2372590A
Cited
US2492678A
Cited
US3068373A
Cited
GB1436191A
Cited
US4282451A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-10 | 1987-04-11 | 1987-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-10 | 1991-04-11 | 1991-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-10 | 1995-04-11 | 1995-10-11 | $7700.00 | Window Closed / Lapsed |